You can only live your life right here and right now, everything else is just an illusion and can only happen in your mind. But while you're focusing in dwelling in past thoughts or being anxious for the future, who is living your life? No one, because only you can live it.
No matter what your beliefs are, but if you ain't present in this moment called now, you're not living you life.
The past is gone, you can't change it, you can only have memories of it and you can relive this memories but you can't change the past, what you can do is change the way you relate to the past and how you let it influence your present moment.
Learn from the past, use it to evolve but don't get stuck in it.
Likewise to your thoughts about the future, because the future exists only as a thought when it comes, it comes as present moment. And to build a better future you have to seize this moment, this precise moment.
If you're ok in each moment, so you will be ok whenever that moment occur.
So be aware of your thoughts, you are that infinite space where they occur, just observe them and let them go.
Feel the unlimited awareness of being, be the witness to the Self experiencing itself in all its manifestations in all levels of consciousness.
In order to do that you have to be present right here and right now.