There’s a Seth Godin’s post that I always use as a reference:
Gravity is a constraint. If you’re a designing an airplane, it would be a lot easier without gravity as a concern, but hey, it’s not going away.
A problem is solvable. A constraint must be lived with.
The art is in telling them apart.
Source: Problems and constraints
This post always reminds me of that old saying that tell us pick our battles carefully. Specially if the battle is a constraint.