mindfulness thinking about future and past?

Is there such thing as mindfulness thinking about the future or past? I have a job that requires a lot of "going" into the future and past (projecting forward and assessing the past).

If you look at the Abhidhamma each though has either pleasant, neutral or unpleasant sensation associated with it. (Ref: Comprehensive Manual of Abhidhamma). These cover all the 4 Satipatthana. You have to be mindful of the arising and passing of these sensations with equanimity. This method is given Pahāna Suttas (Pahāna Sutta, Avijja Pahana Sutta 2).

From what I understand, mindfulness practice has to do with staying in the present.

No necessarily true. This is the general thought this way so students do not make mistakes in practising the instructions. The instuction and easier and simplified also. Saṃyutta Nikāya > Saḷāyatana Saṃyutta > saṭṭhipeyyāla gives practising on the past, present and future 6 sense bases, 6 faculties, 6 external objects, 6 contacts from the respective faculties, 6 feelings from the particular contacts.

When you must plan for future business then simply note something like, "planning planning" in the present moment when you are planning. If you don't note then simply intentionally focus your awareness on the planning but I recommend noting at least in the beginning.

When remembering the past then always make sure to note 'remembering, remembering", in the present moment, moment by moment as the "remembering," arises. Does that help?

Mindfulness thinking about future and past?

Actually any object can be taken as a meditation-object, it does not matter if the object is a physical or mental phenomena.

If you are practicing Vipassana meditation (insight meditation), then you have to be with reality in the present moment. That is the foundation of the technique.

When you are on the job and working with past and future you can be mindful of the thoughts, ideas and other mental formations, as they arise and pass away. If you observe them with mindfulness, in the present moment, then you are practicing correctly.

If you are getting lost in the thoughts, that means that mindfulness is absent and the Mind has followed after the object or run away from the object. When one is mindful, the Mind is kept in the present moment, unable to stray from the object.

Is there such thing as mindfulness thinking about the future or past?

Thinking about past and future is actually done in the present moment, since past and future are concepts and do not really exist. There is only the present moment.

The tradition I practice (Mahasi Sayadaw, The Burmese Method), has a technique of noting. There is already an answer in the thread which describes the noting. If one is thinking, then one makes a mental note saying "thinking, thinking" while sending the Mind out to the object. That means that full attention has to be placed on the object (in this case mental formations), while the mental note is being applied.

When one has observed and noted the object a couple of times, one places attention on the feeling of the rising and falling of the abdomen. The abdomen functions as an anchor, so that the Mind will not get lost. One keeps attention on the abdomen until a new object arises, then one notes that object a couple of times and again returns attention to the rising and falling of the abdomen.

The function of the noting is the remind oneself to stay in the present moment and to stay objective. This way the Mind cannot identify with the objects. Instead one is seeing their ultimate reality, i.e. the 3 marks of existence; Impermanence, Unsatisfactoriness and Uncontrollability of conditioned phenomena.

In this tradition one tries to cultivate insight about the 3 marks of existence. They are gateways to Nibbana.