After 40 you've already made many of your major life decisions - career, partner, education, kids etc. There's less room for new experiences to alter that trajectory meaningfully.
One thing I've also realized through being lucky enough to enjoy some "semi-retirement" between work is having a healthy balance makes me appreciate both work and "leisure" more. It gets pretty boring to go to the beach every day, it turns out. I was itching to get back to building something by the end.