Very important point. I think the older you are, and particularly if you have dependents, you need a longer period of savings. Couple TV programs (e.g. Suze Orman show) advise to have at least 8 months salary worth of savings.
I think if we have that bare minimum of comfort (i.e. 3/8/more salary months), then after that we should try to focus on being healthy. Working more and compromising health is a very bad deal. Even getting over-anxious about things leads to stress (which can lead to bad health).
Most of us programmers like our jobs anyway, provided work/managerial environment is not too bad. If we can just do it in a healthy way (YMMV, of course. 100+ is healthy for Elon Musk, and 40/50 for me).
I think even working towards an early retirement, may also not be a good thing, as some people try to. I have seen people age very fast after they retire. So if we enjoy our work, and are paid a healthy amount, and have decent savings. Should look to live a good life, right in the present. And not worry too much about long term.
Long term: I think for most programmer-entrepreneurs long term is more like a big exit after a few (3-5) hard years of work. The problem happens when realistically only a few of us can have such good luck. So being realistic, we should look at returns for the long haul (10 year periods). So staying healthy and alive, is very much needed, if and when we have the big exit.
I personally, started long(ish) distance running, to attune myself for a long haul work wise. At present work only around 40 hours (M-F). Sat/Sun only when needed (which is rarely). Don't compromise exercise for work. Get it done in the morning itself, before I have a chance to log in.
I also try to minimize the stress. What's a business without setbacks? So there are setbacks, e.g. partners breaking/not-renewing contracts . But I try to think of these things as just -ve events in a series of various +ve/-ve events. There are technical worries as well, e.g. EC2 volumes running out of disk space, within the next archival cycle, and increasing them fsck/resize2fs them, burning them in the image.
But also life goes on...in the present.
PS: Sorry, for not being specific, and randomly articulating even tangential things to the topic at hand. Hope its not too bad. :-)