I learned how to juggle three objects because I wanted to increase my coordination and skill at catching/throwing spherical objects (it didn't help with frisbees). I can show off this new skill, and have more confidence that allows me to stop dodging balls thrown at my head and successfully catch them instead. It's enjoyable, and I've started juggling in between working to move around and relax, hopefully increasing my mood/productivity (I haven't measured).

It didn't take very long to learn this basic skill, maybe 10 hours until the low-hanging fruit were eaten.