Eckhart Tolle says that there is no past and no future. That those are simply imaginary constructs of your mind. That there is only, and has only ever been, and will be, the present moment. The Now.
Let’s assume that he is correct. (He might be.)
If you’ve got a lingering problem, a disagreement or source of tension with someone, such as a family member, friend, or co-worker, then, seeing that the problem does not exist in the past changes things. It certainly can bring up emotions in your body right now. But the shift begins when you realize that those old feelings are not still happening. There are only current feelings, and you can address them with a higher degree of consciousness. For example, “Look Frank, even though we haven’t talked about this before, this is a source of tension for me. I’d like to discuss this so we can release it, and move forward.”
Seeing things as they are right Now might also change the way you look at what, when, or how you eat. Just because you always eat dinner, no matter how late it is, out of habit, doesn’t mean that you have to eat it tonight if your not really hungry right now, and, it’s close to bedtime. Just because you’ve given in to cravings in the past doesn’t mean that you can’t resist them right Now. Or, you might see that you’re not actually in so much of a rush, and you can chew a little slower, even though you usually eat very quickly.
The examples are infinite, and, so is this moment, the present.
You won’t be able to stay in the present all the time; your mind’s defenses are very strong, It will project you into the past and future often.
But you will, with practice, be able to come back to reality more often.