For the record, I did get crippling RSI in my early thirties and this forced a drastic reevaluation of my priorities. Eight years later, and the RSI is manageable but only because I completely changed my lifestyle. Part of that is only working a regular workday, and doing other stuff outside that time. Like running and mountain biking. I quit my "second job" as a Debian developer and general open source contributor because of that. I still do some, but it's strictly casual with no commitments. That's the price for not being physically crippled. You've got to consider your long-term health. Sitting at a desk is terrible for your body. Doing it in the evenings as well is even worse.
Regarding not looking desirable. I think you're a bit off about that. Sane people and sane companies do not work themselves and their staff to death. They want people to be able to work over the longer term, and not burn out. In most of the places I've worked at, working out of hours has been strictly frowned upon. If you can't do your assigned tasks within work hours, that indicates a management failure in assigning you too much work, or in underestimating how long it would take, or in overestimating your capabilities. There is a reason we do all of the sprint planning and backlog refinement. It's to ensure no one is over- or under-worked over the long term by having a consistent and (most importantly) sustainable workload. If someone did find themselves having to work longer hours, the first thing they should do is tell their manager and get the situation fixed. Not to pull out all the stops and burn the midnight oil.
The younger me would have been that person. But part of getting more experience is learning to say "no". No matter how much work you do, there will always be more work the next day. And you will rarely be thanked or acknowledged for going above and beyond the call of duty; ultimately you have to look out for your own self-interest as well as the interests of the company. Sometimes there are good reasons to work overtime, but that should never be a routine part of your existence.
My personal experience of people who work crazy hours is that they wear their "heroic" efforts like a badge of honour, but the work itself is often terrible. (And I include myself here.) When called out upon this during code review, you get excuses like "yes, but it was 2am on Saturday". "OK, but it's Tuesday now, why didn't you review it in the cold light of day and fix all of these obvious defects? We don't lower the bar just because you chose to work late while very tired."
Keep yourself healthy and sane for the long haul.
