I'm up somewhere over a dozen of them, and I live in CO. If you're in otherwise good shape, you can nail the easier ones, just listen to your body. If you're out of breath, stop and wait for a few minutes, then push on, repeat as necessary. If you start feeling intensely lightheaded or develop a good headache, bail. Drink more water than you expect to need of course. Also, take the start times seriously. Get on the trail by four or four thirty, you'll have lots of company but it gets seriously awful with crowding later on, and you really do not want to be on the mountain when the afternoon summer storms come in.
You can also go on plenty of other Colorado hikes, still get a great workout, and stay under 13k feet and see incredible sights. 14ers are fun to cross off the list, and every CO tinder profile is required by law to have a pic on a summit, but they're crowded and often more fun in retrospect than they are at the time. That said, they are pretty. A few pics I have uploaded.
Those are really enjoyable pictures. Would you mind giving the locations. The second time that my wife and I drove to the peak of Mt. Evans there was a sign at a gate at about 12,000 ft. telling you that the road had not been maintained and to proceed at your own risk. We went on to the top and there was no one on the road or at the peak. There was no weather close to us but you could look down the peaks and see rain showers or sleet, you never knew which one.
Sitting up there for probably an hour left visions that I can see today, many years later.