Yep...I ski or hike, on western trips,a few times per year @ 10-12 thousand feet & other than a noticeable shortness of breath (compared to lower elevations), never had a problem.
But several people, lately, have told me stories about people that do have some trouble, so I thought it worth mentioning.
Especially for those doing the really high stuff...
It is worse if you fly in and have no time to acclimatize. If you ride/drive, your body has more time to adjust.
They recommend not sleeping over @ 7,000 feet the 1st night.
FYI:
Manitou Springs, CO is 6,320 feet.
Idaho Springs, CO is 7,555 ft
Montrose, CO is 5,806ft