The best advice I can give you comes from the following quote "You'll never outperform your own self-image"
Basically, the reason you struggle in the changes you seek is because your reality, the one that you created and believe, is that you will struggle.
It's the same reason people who go on diets fail. They rely on willpower and willpower is never a long term solution. The long term solution is to get clear and focus on you becoming who you want to be, not who you were yesterday or even 5 minutes ago.
Once you can begin to see yourself as committed, and as a person of action who always follows through on his goals, then the real transformation takes place.
So start right now by focusing on a new self image of yourself. Focus on being the strong, committed person of action and that's who you'll be.