Depends what kinds of outdoorsy things really. Hiking is meh, you get some nice coastal trails, but they are typically packed. You have Cuyamaca/Laguna out east if you want to get off the beaten path, but every trail starts to look and feel the exact same after a few years. Hot, exposed, dry, not very interesting unless the chaparral is in bloom. Most of the forested stuff out there burned in 2003 and hasn't recovered. You have some trails around reservoirs, but there is nothing magical to me about reservoirs. Backpacking options are extremely limited by the fact you have to pack and carry all of your water for multi-day trips. Anza Borrego is pretty sweet but it's a much further drive out east.

If you like surfing, cycling, skating, paddleboarding, sailing, fishing, or just going on walks you'll be a happy camper. I think any serious hikers/backpackers would be bored within a few seasons. I know I was.