To stay true to your goals, enlist the help of a friend or join an online support group. It helps to have support from people who are going through the same thing. You will be surprised how much an "atta boy" or "way to go" can lift your spirits and keep you motivated through rough patches.
One of the keys to improving personal development is to let your emotions out. Many people hold their emotions in which only adds to anger and depression. It is okay to cry or let your anger out sometimes. If you are especially frustrated, you could take it out on a punching bag.