Proof

"Times are tough, that is the truth, but what's succeeding without a proof?"

 All of us struggle through life, but in the end when it all works out, those struggles become the stories you pass on as proof to yourself and others that you have work hard to go this far.

Time

"A precious moment in time is more valuable than all the earth's riches combined"

A picture may be nothing much now but when you look back at it after many years has passed, you will then realize its value for no matter how much money you spent, there is no way for you to return to that moment in time anymore.

Breathe

"When you feel like breathing and something takes your breath away, be calm and move along rationally." 

When you finally feel you can relax and then something happens, accept it and go along with it in the needed pace because life is unexpected, so you gotta go along with whatever it gives you.