Souffrir pour être costaud sur le balcon romantique

What does “costaud” mean in French?

Costaud describes something or someone solidly built: a burly person, a sturdy table, a full-bodied wine (un vin costaud). It is informal without being rude, and it lands roughly where English puts “beefy” or “hefty.” It stretches to difficulty as well — un dossier costaud is a weighty file, un examen costaud a tough exam.

The line il faut savoir souffrir pour être costaud is a swap on a much older French saying, il faut souffrir pour être belle — “beauty is pain,” already in circulation by the 17th century. Putting costaud where belle belongs is the whole joke: same suffering, gym version.