We did this with Shawn’s family and had a blast! Rent bikes or e-bikes and ride about 9 miles to the neighboring town of Frisco. We stopped at Dillon Reservoir for the views. It’s paved and described as an “easy” trail, but some of those hills will get you. Explore the town of Frisco then bike back to Breck or drop the bikes and take the free shuttle back.
Take a free gondola ride up to a base camp area with zip lining, mini golf, dining, hiking, etc.