It can reduce stress.
Most scientific research has generally supported the idea that exercise helps to ease stress. Bicycling is very much a part of that, but it’s also worth considering that bike commuters have reported lower stress levels than their counterparts using cars and mass transit, as found in a New Economics Foundation study last year. A 2006 study by the Victoria Transport Policy Institute supports this—a much higher rate of cyclist commuters reported liking their commute than people making their way to work using other vehicles. Just another reason to consider doing a bike commute.
You can do it for charity, much like a 5K or 10K run.
There are plenty of bike race events out there held to raise money for great causes, such as cancer research, multiple sclerosis research and local organizations. Have a look at what’s going on in your area—most races give options as to how far you want to go so you won’t have to jump right into the 100-mile race after taking a few leisurely rides.
Exploring and really getting to know the area around you better.
Most of us fail to fully explore the area around us. Even if you run outdoors regularly and mix up your route often, you’re not getting close to the range of travel and exploration you can experience through riding your bike. Even if you decide to bike in areas you usually drive by, you might be surprised by what you notice and appreciate being outside taking it all in.
For your sense of freedom and above all, for fun.
The moment a kid realizes s/he’s able to ride a bike is always a moment of elation and often a defining childhood moment. Biking may have been your means of freedom in those earlier years, but it might have also given way to the newfound independence of driving a car as a teenager. While driving can lose its novelty when you're sitting in traffic day in and day out, biking continues to be offer fun and freedom. Enjoy the outdoors like a kid again and hop on a bike.