This ^^^^. I am in my thirty ninth year in embedded development, started the year I turned 27. (yeah, do the math) I have strictly limited myself to 40 hour weeks following a severe burnout in the late 1990s.

I could retire now, if I had to, but I hope to do this for another three to five years. It is just far too interesting and fun. I had an older coworker that worked full time until he was 74. He also just enjoyed the work and the people he worked with.

It is a marathon, and change is constant, which makes it more interesting than a lot of careers in the long run. Plan for the long run, and make room to live your life all along the way.