If you are looking for a local, easy introduction to kayaking, and a good excuse to get outdoors on a sunny afternoon. Check out the boathouse at Lake Merritt in Oakland. They rent all kinds of boats for reasonable prices. The lake is flat (although it can be windy, so bundle up!) If you have little to no paddling experience, and are intimidated by more ambitious treks, I'd say give it a shot on the lake. It's small, so you can't go far, but it'll give you a little taste, and certainly get you some fresh air.