The amount of opportunities available to me just grow year after year, because I get to know more people (which also move to different companies), that would like to work with me in the future.
Just be a person that ships, makes things work, in a friendly mood and you are set for life.
People you work with also grow in their careers, which means that often enough, they make the calls on who gets hired and who doesn't.
I think that during your 50s, you should have built a good "base," though, like paying off your mortgage. You should have more leeway to actually take life in a less demanding way, so perhaps do some consulting or not work full-time and earn a living to retire in peace.