The Serenity Prayer is sound advice ......God, grant me the serenity to accept the things I cannot change,
Courage to change the things I can,
And wisdom to know the difference.
I think we go through different stages in life and I believe we do get wiser as we get older. When I was 17-30 I thought I was bulletproof, then marriage and kids settled the jets somewhat, busy being a full time taxi for the kids, late 40's and now well into 50's kids flown the nest, major health scares survived, mortgage free, enjoying life and looking forward to retirement.
Personally speaking I would not like to be 18 now, think there is too much pressure on young people, especially with 'social media' and so called celebrities. Took me a long time to accept that I can't change the world but eventually I did and life is good.