Turned 50 today.
Didn't feel any different when I had a close call last year. Many people say they do, some may actually feel it. I just lost a week and had to recover over a month or two, with the major strain placed on my family and friends, but turning 50 has put an actual (artificial) marker on the process of earning wisdom. Everyone likes to think they are on the right side of half way, but 50 is realistically more than half way for anyone. My wife's family are notoriously long lived, the women of the family usually reaching the mid '90's or even a ton. My lot rarely make 80.
Do I feel different? Maybe a little more aware of time and how much is left.
Notes to younger self;
Avoid the things you really don't want to do, unless they must to be done for the welfare of others.
Complete tasks by following natural paths of inspiration (Wu Wei). Find flow.
Don't worry, as it wastes valuable time and resources.
Don't waste time.
Make the best choices you can, to avoid re doing things. Work out the end point and go straight there, avoiding miss steps.
Take more photos, travel more, see more. Buy (and obsess about) less gear.
Let go of regrets (see above).
See the good in things and people instead of ugliness/opposition/unhappiness/ignorance/fear.