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.