Lots of people pick up garbage "for fun". Where "for fun" means "because they care and it's the right thing to do". And by lots, I mean it's such a common thing there are thousands of organisations around the world who do it. There are multiple national days in many, many countries based around picking up garbage. I myself have organised several beach clean-ups for a local group as part of a larger nation-wide beach clean up day.

Look up the organisation "Trash Hero" for another example.

Then there's the engineers who work on ways to clean up the Pacific Garbage Patch.

There's people who clean up slobs' tables in fast food places because it doesn't take any extra time to help out when you were going to do it anyway.

The point is: who picks up garbage for fun? Everyone else but you.

As for nurses... there are huge international volunteer organisations based around doctors and nurses volunteering their time. How have you never heard of any of this before?