Time is normally broken into past, present and future, as if they are equal parts, but are they?
The major difference is that while the past and the future are infinitely large, the present is infinitesimally small. So what makes the present so important? The past cannot be changed. It has happened, despite what you might not want to remember, or what you might have wanted to happen. There is no point in regretting what was done, or not done, in the past. The future is relatively unknown. You cannot be sure of anything in the future, regardless of your hopes and wishes. But there is one major difference between the future and the past: you can change your future.
And this is where the present gets its power, as it is the only time when you can make a decision and choose what you do, and that will change what happens to you in future, to a degree dependent upon the magnitude of the choice. If you choose, and take immediate action upon that, you may immediately change your future, so what you choose needs consideration, so that you don't set in train a future that you do not want.
If you make a choice, and keep making the same choice when required, you create a thinking and action pattern that becomes a habit. This is how you change your habits: by making the required decision in a lot of present moments. If you build a set of new habits like that, you build character for yourself. You have changed who people will see you as. You have reinvented yourself, so there is no excuse to say
that is who I am, because the you who you identify with can be changed by you.
The present is your opportunity to change your future, because that can happen at no other time, so use the infinite number of chances you are given to change yourself.