One cannot make an omelette without breaking eggs. This idomatic expression, meaning it is difficult to achieve something important without causing any unpleasant side-effects, has been my lifelong mantra.
And, as one can see in the edit history of my English Wikipedia User page... even uttering the phase on Wikipedia will get you a "speedy deletion warning"!
- Originated in French (on ne saurait faire d'omelette sans casser des œufs) as early as the 1740s and made its way from there into English. (According to Mike Vuolo, Slate.com)