Plenty of definitions for stretch goals exist. The term crosses over between the corporate world and endurance sports.
Stretch goals involve expectations that go beyond current capabilities. In simpler terms: a stretch goal is best defined as a goal that combines exceptional performance with high quality training and a really great day. Some people set stretch goals based on the people around them.
For example, plenty of athletes say, “I want to break four hours at my marathon” or “I want to go under 5:30 hour for my half-IRONMAN race” or “I want to win my age group at a sprint triathlon."