You couldn’t ask for better weather or for a more idyllic setting to play outside. Start with a walk down by the ocean. You will enjoy looking at the caves, the seals and the other ocean wildlife. A nice dirt path takes you up on top of the bluff overlooking the bay and gives you a glimpse of many of the beautiful homes.
If you are feeling a little more adventurous, rent a kayak and spend some time on the water. Several outfitters are available for rentals. Or if you are extremely adventurous, take a swim in the bay. A course is set up for regular swimmers and triathletes. I have done this swim on an earlier visit, but I am definitely on the extreme end of travelers. Also, I had just done the Escape from Alcatraz triathlon in San Francisco so I was in pretty good shape.
I would also recommend, renting a mountain bike and riding the scenic drive around La Jolla. There is no better way to see the beautiful scenery and homes and do it in a way that is true to the spirit of La Jolla.