activities for young boys

Did you just move to Antioch? There is a water park that they would enjoy I am sure. But I would also take advantage of the fact that you are so close to all the u-pick farms in Brentwood. It's always fun to go pick fruit and dry or can them even if you're a boy. There is also a YMCA in Antioch that might have some fun activities. I believe there is also a skate park and pool in Antioch that they might enjoy that's run by the Antioch parks and recreation.

where can you go fruit picking?!

Brentwood is pretty nearby. There are a ton of farms in Brentwood. The season for summer fruits is almost over now, but you can call or check the website:
http://www.harvest4you.com/

We also have quite a number of reviews of Brentwood farms here on Trekaroo
http://www.trekaroo.com/places/brentwood-california/activities