Take part in Colorado's booming cycling culture—at least for the day. During this environmentally friendly and stress-reducing ride to and from work, thousands of fellow residents will ditch their cars and rush-hour traffic to promote the benefits of commuting on two wheels. Wed, times vary.

Hike and climb in Boulder’s foothills to help the HERA Women’s Cancer Foundation raise funds and awareness for ovarian cancer research.

Help fight cancer, one mile at a time. This two-day bike ride covers more than 80 miles, from the Anschutz Health and Wellness Center in Aurora to the Colorado State University Flint Animal Cancer Center in Fort Collins. Not enough? Try the additional 60-mile loop in the foothills on day two. All proceeds benefit cancer research at the University of Colorado Cancer Center. Sat-Sun 8 a.m.

We always appreciate a contest that caters to both the competitive set and the just-for-fun crew. This cross-country bike race does just that—and throws in some philanthropic motivation.

Each year, 20,000 Coloradans are diagnosed with cancer. This stair-climbing event aims to raise funds and awareness for cancer organizations. A “stairless” course is available for those unable to—or who would rather not tackle—the 33 rows of stairs. Sun 6:30 a.m.

As you run five kilometers, spectators bombard you with colorful paint. At the end, runners' pearly white T-shirts will look more like a rainbow than a racer's uniform. Sat. 9 a.m. - 11 a.m.

In this race, being mentally sharp is more important that being physically fit. Teams of two to four people solve clues and face challenges while navigating Denver via foot and bus. Sat 11:30 a.m.

This bash brings audiences up close and personal with classical small ensembles. Hearing classical music the way it would have been herd hundreds of years ago, listeners join players is small rooms and get so close they may eel the floor vibrate with each movement. Dates, times vary.

Don't want to run a 5K? Dance through it instead. During this race, runners and dancers alike traverse miles of neon-lit tracks. Participants are encouraged to add to the light show with their own glow sticks and LEDs. Fri 8 p.m.

Finally, an excuse to play cornhole without having to attend a football game. The Throwdown is a fundraiser for the Cottonwood Institute, a nonprofit that connects kids with the outdoors. Participants are guaranteed three games with a four team, round-robin format. Sat 11 a.m.-4 p.m.