Sometimes mine help, sometimes they don't.
When they don't, I set up a childcare trade with a girlfriend. I'll take her kids for a day and she'll take mine a different day. The kids get to play and we get a chance to relax, catch up on our work, or do an outside project.
Or I do it while my husband is home and he'll hang out with them.
Otherwise, they hang out with me and do age appropriate tasks. This morning, for example, I scraped paint off a cast iron tub. One sat on the toilet while the other hoped around in the door way. It was fun, they were rooting for me and proud when I finished. I didn't let them help because I was using a razor tool (they are three and four and don't have much experience with knives).
A few weekends back I hung new trim in our bedroom. I had the kids pass me up tools and finishing nails. They were actually a GREAT help.
I wouldn't have mine help me with painting unless I were able to have them take turns. I don't think I could keep them both on task enough to not make a mess. Although, I'd have them help with an outside painting job I think (never happened, so I don't know for sure).
Good luck and happy painting!