Living near sea level, I tend to run out of energy exercising above 6,000 feet.
Since all the interesting alpine hikes in the summer and early fall are at or above 6,000 feet, I look to do a few higher-elevation conditioning hikes.
In early August I drove to Timberline Lodge at 5,900 feet and began hiking up the south climbing trail on a gorgeous day.
Nearing the top of the Palmer Lift at about 8,000 feet, I looped back to the southwest through the rocky terrain. Eventually I hit the Pacific Crest Trail and hiked back to the Lodge.
A very nice way to spend the morning.