His interest in the Himalayas was sparked in high school by reading Maurice Herzog's account of the first climb of Annapurna, titled Annapurna. After climbing Kangchenjunga in 1989, Mount Everest in 1990 and K2 in 1992, Viesturs became an international mountain guide and was sponsored for full-time mountaineering. He served as a guide for Rob Hall's Adventure Consultants company during their 1995 Everest expedition. Viesturs climbs with Finnish partner Veikka Gustafsson.