I know this is just one person who was in a different time and under different circumstances, but I've found it inspirational to put age into perspective. Grace Hopper first entered computing at age 38, completed the first compiler at age 46, influenced the design of COBOL at age 53, wrote COBOL for the Navy through her 70s, retired from the Navy aged 80 and only then became a consultant for DEC. So for me , at least…
And to continue the Grace Hopper example... Remember that she transitioned to computing from being a Mathematics professor at Yale, so she was able to leverage her previous training into the new career. Try and do the same if you can. Leverage what skills you've already gained to switch into a career where they are a big advantage. Then you are starting nearer to those already in the field, not the beginning.
Absolutely. In many cases, there are often a wide range of related/adjacent jobs that are significantly different in various ways but can nonetheless be a fairly natural transition. (Though key word can. I've seen examples that worked and examples that didn't.)
On the other hand, I'll go back to school and get a Masters degree in this very tangentially related STEM field is probably going to be a lot harder.