No pain, no gain (or "No gain without pain") is an exercise motto that came into prominence after 1982 when actress Jane Fonda began to produce a series of aerobics workout videos. In these videos, Fonda would use "No pain, no gain" and "Feel the burn" as catchphrases for the concept of working out past the point of experiencing muscle aches.
The bodybuilding community adopted the phrase. It expresses the belief that solid large muscle is the result of training hard and suffering sore muscles repeatedly, implying that those who avoid pain will never reach a professional level as bodybuilders.
In terms of the expression used for development, the discomfort caused may be beneficial in some instances while detrimental in others.
The expression has been adopted in a variety of sports and fitness activities.
The expression has also been adopted in other areas, notably as a slogan implying that attempts to make progress in some personal goal which avoid discomfort are, in a way, illegitimate or cheating, and probably, in the view of the speaker, will fail or not last, because of the use of a shortcut. For example, weight loss which is achieved through stomach surgery rather than by the long-term self-denial of dieting.
David B. Morris wrote in The Scientist in 2005, "'No pain, no gain' is an American modern mini-narrative: it compresses the story of a protagonist who understands that the road to achievement runs only through hardship."