Is there a point for a not continues practice?

I've once heard a Buddhist nun saying If you say "I can't do it" it almost always means "I don't want to do it". I felt a bit caught hearing this the first time. But it seems to be true, if the mind is always thinking about the future, what might happen and what might not happen, what you will gain or what you will loose, or if it's thinking about the past it's really impossible to stay present have and sati and rememeber what's actually happening. The (so called untrained) mind will do anything to escape the present moment. Therefore a inconsistent practice is far better than no practice at all, because a inconsistent practice can become consistent ... through practice. But if you don't practice at all, there is no practice that could become consistent. So if your aim is a consistent practice you continue being inconsistent until you're consistent. Also what do you think is practice? Do you mean only formal meditation by saying 'practice'? It's not quantity but quality that is important. I.e. If I were to ask you "In what posture are you in right now? Sitting, Lying, Standing, Walking?" and you'd remind yourself "I'm sitting (or else)" then this moment of reminding would be practice, right?

I've made a small collection of motivating and inspiring references/quotes from the teachings:

From SN22.101

"Suppose a hen has eight, ten, or twelve eggs: If she doesn't cover them rightly, warm them rightly, or incubate them rightly, then even though this wish may occur to her — 'O that my chicks might break through the egg shells with their spiked claws or beaks and hatch out safely!' — still it is not possible that the chicks will break through the egg shells with their spiked claws or beaks and hatch out safely. Why is that? Because the hen has not covered them rightly, warmed them rightly, or incubated them rightly. In the same way, even though this wish may occur to a monk who dwells without devoting himself to development — 'O that my mind might be released from effluents through lack of clinging!' — still his mind is not released from the effluents through lack of clinging. Why is that? From lack of developing, it should be said. Lack of developing what? The four frames of reference, the four right exertions, the four bases of power, the five faculties, the five strengths, the seven factors for Awakening, the noble eightfold path.

From the Dhammapada (II. Heedfulness)

[21.] Heedfulness is the path to the Deathless. Heedlessness is the path to death. The heedful die not. The heedless are as if dead already.

[26.] The foolish and ignorant indulge in heedlessness, but the wise one keeps his heedfulness as his best treasure.

[29.] Heedful among the heedless, wide-awake among the sleepy, the wise man advances like a swift horse leaving behind a weak jade.

From Ajahn Chah: Food for the Heart (Chapter: Steady Practice)

I didn’t know what to do, I was baffled. Then I realized that the practice which is steady is the important thing. One must practice consistently. They call this the practice that is “consistent in all postures.” Keep refining the practice, don’t let it become a disaster. Practice is one thing, disaster is another.

Most people usually create disaster. When they feel lazy they don’t bother to practice, they only practice when they feel energetic. This is how I tended to be. All of you ask yourselves now, is this right? To practice when you feel like it, not when you don’t: is that in accordance with the Dhamma? Is it straight? Is it in line with the teaching? This is what makes practice inconsistent.

Whether you feel like it or not you should practice just the same: this is how the Buddha taught. Most people wait till they’re in the mood before practicing, when they don’t feel like it they don’t bother. This is as far as they go. This is called “disaster,” it’s not practice. In the true practice, whether you are happy or depressed you practice; whether it’s easy or difficult you practice; whether it’s hot or cold you practice. It’s straight like this. In the real practice, whether standing, walking, sitting or reclining you must have the intention to continue the practice steadily, making your sati consistent in all postures.

From AN06.055

"Now what do you think, Sona. Before, when you were a house-dweller, were you skilled at playing the vina?" - "Yes, lord."

"And what do you think: when the strings of your vina were too taut, was your vina in tune & playable?" - "No, lord."

"And what do you think: when the strings of your vina were too loose, was your vina in tune & playable?" - "No, lord."

"And what do you think: when the strings of your vina were neither too taut nor too loose, but tuned1 to be right on pitch, was your vina in tune & playable?" - "Yes, lord."

"In the same way, Sona, over-aroused persistence leads to restlessness, overly slack persistence leads to laziness. Thus you should determine the right pitch for your persistence, attune2the pitch of the [five] faculties [to that], and there pick up your theme."

From MN131

You shouldn't chase after the past or place expectations on the future. What is past is left behind. The future is as yet unreached. Whatever quality is present you clearly see right there, right there. Not taken in, unshaken, that's how you develop the heart. Ardently doing what should be done today, for — who knows? — tomorrow death. There is no bargaining with Mortality & his mighty horde. Whoever lives thus ardently, relentlessly both day & night, has truly had an auspicious day: so says the Peaceful Sage.

If you take ups a sport and do irregular practice there will be some benefit but you will not react your true potential which you perhaps can reach with regular practice. Practice of mindfulness is also similar.

You should consider the following

Change your approach

In Mahayana Buddhism the emphasis is on skillful means, sitting meditation is not the only practice available, there are plenty of other Dharma practices you can do, build up your base of merits first. You could focus on chanting a particular passage or mantras, this allow your mind something to focus on, and you will naturally see mindful concentration arise through this practice, even without trying to sit.

You could attend services, try to participate in any group chanting if available - Theravada is far as I know is not available for lay people in this case. But there are plenty of Mahayana Buddhist temples that offer group chanting with lay people.

You could offer to help clean up the temple, cleaning is also a powerful practice for mindful concentration if you can focus on what you are doing. Zen monks can do chores like cleaning and still experience Zen also known as Jhana. They blissfully and mindfully perform the tasks needing to be done. Go forth and volunteer! In fact, just participate and enjoy the community, you will learn something!

You can practice offering alms to your community of monks, giving is a great practice of Dāna and give rise to skillful mental qualities. In fact before you try to focus your mind on sitting meditation, try to cultivate positive qualities like love, kindness and avoid negative ones like anger in your daily life.

As you build up your merits, you will find it easier to sit because your mind will naturally begin to calm.

Know that your effort makes a difference

Yes a consistent practice is of course better, but even one single change of thought will make a difference no matter how small. Take comfort in this. Have some confidence in the fact that even when you don't seem to be 'getting somewhere' at least you are not doing something harmful, and that is already making a difference, and if you are not advancing, at least you are not sliding towards more suffering.

And your actions will eventually create the causes and conditions favorable to further your path, whether it will take years or life times. Have some faith.