I had a very similar experience around 37. My latest startup had crashed, and I sort of woke up to the realisation that (for the first time) not all paths were

I had a very similar experience around 37. My latest startup had crashed, and I sort of woke up to the realisation that (for the first time) not all paths were open to me anymore. To some extent I think this is just part of the natural cycle of life: the mid life crisis if you will. Looking back I think some of the feelings of regret and rumination on the "road not taken" was more or less symptoms of depression / acute crisis. That part will pass. Exercise helps. For me it was also a lot about questioning the value system I had been born into and finding my own. And I don't mean just the high and mighty (political) values that we talk a lot about, but the really low level stuff we're often unaware of. If I had $500k in the bank and was in this situation I'd definitely try to find a good therapist (the freudian type - not KBT), and talk about your attitude to work, self-esteem, relationships and values. For me this was a period of pretty dramatic and profound change. I have a feeling you could have it easier. If so I'd also consider putting some effort into finding a partner, and perhaps having children. But health comes first!