[_mlbt]

As others have said kids. Even if you don't want to have your own or adopt any, find young people to mentor in some capacity. It could be your nieces or nephews, neighbors, or kids you work with through a volunteer organization. If you're into sports junior and pee-wee leagues are always looking for coaches.

Also just in general change your mindset to being a producer and a giver instead of a consumer and a taker. Taking up a hobby such as wood working, leather working, or music where you can produce some tangible result for your efforts can do wonders for your mental health.