Updated: Aug 7, 2019
You can't make up for lost time.
Once it's gone, it's lost forever.
All you can do is live today to the best of your ability.
While you're at it, try to learn something so that you can live tomorrow a little better.
"One today is worth two tomorrows."
"Lost time is never found again."
"You may delay, but time will not."
"Dost though love life? Then do not squander time, for that's the stuff that life is made of."
- Benjamin Franklin (maybe...considering the frequency of quotes incorrectly attributed to historical figures...)
Our time on Earth is finite. Make the most of it.