Here are some expressions to help motivate you:

1 It is not the size of the dog in the fight, it is the size of the fight in the dog.

2 To him who is determined it remains only to act.

3 Some men have thousands of reasons why they cannot do what they want to, when all they need is one reason why they can.

4 You can either advance boldly in the direction of your dreams, or retreat fearfully into the safety of the habitual.