I started running some months ago and currently am able to run up to 30min nonstop (I often combine it with walking beforehand and afterwards). I usually run different routes, often they include hills as well. I live at sea level and will spend a month at a much higher altitude (about 2,700 feet high). I plan to keep up with my running as I am used to run every day now, plus I am training for a 5k in the fall. I used to live at a high altitude for 20 years, then moved and have been living at sea level for over 10 years. So usually when I am at an higher altitude it doesn't really affect me, although last year at Big Bear (about 6,000-7,000 ft) I noticed it did affect me. Any advice on how to switch from low altitude running to high altitude running? oh I will be jetlagged for a few days so this needs to be taken into consideration, too.