Kieran Setiya, an MIT philosophy professor, wrote a philosophically informed self-help book. It’s called Midlife: A Philosophical Guide. That doesn’t sound like it would work. But I found it helpful as a person who just turned 40 and wants to think and write about it.
Setiya approaches midlife from the perspective of diagnosing and solving the ‘midlife crisis,’ which, as he points out in the first chapter, isn’t a particularly old idea. At least in its explicit form. Rather than a crisis, midlife is really more of a vantage point. The person at midlife can see both a long past and a long future. Maybe the past worked out for them, and maybe the future will.
Or not.