We rode Black Star Canyon here in Orange County CA Sunday. Its one part of the Santa Ana Mountains that did not burn last month. Just a few miles away from the evil Riverside Freeway but the view & feeling at the top, are worlds apart.
Cycling is at a peak of popularity in the US. Lance Armstrong certainly educated & inspired people to get involved. Mountain Biking just keeps building on it's base set down in the '70s by Joe Breeze, Gary Fisher & Tom Ritchey.
Fitness trainers recommend finding an activity that you enjoy doing. Riding a bike is a low impact aerobic workout that builds leg & upper body strength and its FUN. Cycling puts you in our natural environment where humans belong and of course, you never forget how to do it. Its an inclusive sport with as many variations as there are people to think them up. Competitive racing is brutal in every class and age group. We may all fantasize qualifying for a National Championship but like other sports, a tiny percentage rise to the top. Don't let that fool you, because bike riding is also more laid back than ever on the Trails, Mountains, Back Roads, in Empty Lots, Fund raisers, Touring.... everywhere.
If you want to start riding, find a friend or a group locally, do some reading to get a feel for the gear and what interests you. You probably have a bike in the garage already that with a tune up, will be fine to start on. I rode a $100 Huffy (36 lbs, w/ a kickstand) to the top of the San Juan Trail in 1999. This raised eyebrows but no one broke out laughing at the top of the 3,500 ' climb. Go out and get your feet wet. Depending on your physical condition you may want to have a stress test. Build a fitness base gradually, it will pay off later when you avoid some injuries related to a more macho approach. Pick up a training guide learn some technical work outs and how your body processes oxygen H2O and nutrients. Come up with a strategy that works for you with realistic goals, then make adjustments. A healthier lifestyle is likely to develop right along with all of this.
Don't be intimidated by the elitist equipment quagmire. Visit some local bike shops (LBS) when they are less crowded. There are no dumb questions, but ask the intelligent ones too. Most creidable LBS people are there because they love doing it (not for the big bucks). When you feel comfortable somewhere, that's a good thing. Shops usually have weekly rides to check out.
Before you know it you will be riding like you are 12 again.
On an adventure of your own making.