Everything that has ever happened is in the past; we only have the present.
Smarter people than I have put a lot of thought into this, the prevailing wisdom is that time is not real; it’s just something we made up to record or coordinate. I agree with this intellectually, but when I’m waiting, time seems genuine, if not slow.
Attention is like a sail. When focusing on something, we move through time quickly. Maybe that’s why time seems to move faster as we get older. The more our attention is focused, the more time seems faster. If now is all we really have, it stands to reason that awareness at the moment is more precious than we think.