Yeah, I realized that the villagers did these, but I didn't think any of them where useless.Here's my theory:

Relaxing: helps prevent work related-injuries

Laundry: helps prevent sickness

Swimming: raises farming and might prompt villager to fish (if currently possible)

Exercise: Helps raise that villager's life span (and raises building skill-courtesy of Jazzo)

But those are just my theories (SP?)...