I'm 78 years old. That's plenty old enough to look back and ask this very question.
Would I want to relive my life and make a few changes? Not a chance.
Some of it has been good, some bad, some exciting, some dull, some opportunities seized, some missed. So, yeah, improvements could have been made but, what if in making those improvements, in seizing those opportunities, I missed out on a course of action that would have led to so many of the happy times?
Like everybody else, I just played it as it seemed at the time and didn't waste time regretting bad judgement or missed opportunity. Omar Khayyam may have been thinking along those lines when he wrote, Take the cash in hand and waive the rest; nor heed the murmur of a distant drum.