A key aspect of coaching is that over time you start seeing your situation differently and become aware of how your thought patterns are responsible for you being in the place you are. New ways of being, new ways of thinking will open up new possibilities for action. And for action to be consistent accountability is critical.
Coaching works because the coach becomes that one person to whom you decide to be accountable to. That itself works wonders because the primary aim of coaching is to move you into taking action; especially on those aspects of your life that are important to you, but you have been stuck.