Squirrel...I think that if you feel good at the zoo, then it's a healthy way to
1) exercise, because you are walking around
2) elevate your mood
3) use your mind, because you are learning things about the animals
4) helping, because you are supporting them with your membership
5) being social, because you are meeting new people...

and the list can go on and on.

I think you are AWESOME for keeping yourself occupied and doing something you love.