To take stock of one´s life.
To make a fresh start.
To put one´s money where one´s mouth is.
The road to hell is paved with good intentions.
To be back to square one.
To put one´s heart and soul into something.
To be easier said than done.
To get the ball rolling.
Not to bite off more than one can chew.
Rome wasn´t built in a day.