If you were given a second chance to go back to the start of your life, and you ended up making all the same decisions, then you must be really happy where you are now. If you could go back in time, would you buy the same car? live in the same neighborhood? get the same job?
Happiness is when everything goes for you and others are happy of you,which is an ideal situation anyway. Just be happy of your situation,just as you are...
You mean acceptance of your situation - Most people are never in the acceptance phase since they're willing to change in so many ways, achieve more and reach their goals, it's quite hard to be present at all times, and not think much either about the past or the future, that's what acceptance is "living the moment and being present" at all times.