Willpower is the amount of control you have over yourself. It is your ability to rationally decide between choices.
Willpower is the key to success. Successful people strive no matter what they feel by applying their will to overcome apathy, doubt or fear. - Dan Millman
Willpower is directly related with your mindset. If you mentally think you can’t do something there is no way you can do it in real life. So to increase your willpower try to put a positive spin on every thought in your head and remove al negative ideas.
Phrases like "I can't" shouldn't be in your vocabulary.
You are only as lazy or lacking in willpower as you think you are. - Ken Christian
Willpower is centered around your goals and ambitions. So if you truly desire a certain goal, your willpower in relation to that goal will increase. So keeping this in mind, to increase your willpower you should pay less attention to the process and focus on the end goal and you will automatically feel a boost in your self-control and willpower.
You have to decide what your highest priorities are and have the courage - pleasantly, smilingly, nonapologetically - to say 'no' to other things. And the way to do that is by having a bigger 'yes' burning inside. The enemy of the 'best' is often the 'good.' - Stephen Covey
Willpower is a mental thing. If your brain is low on energy you will become low on willpower as well.
Willpower may be all in your head but this doesn’t mean it’s not affected by external factors. Support from friends and family can be a huge boost to your willpower. So try to surround yourself with people who can motivate you to keep going and give you the extra push when needed.
Why are you exercising? Why are you quitting cigarettes? Why are you quitting your old habit and starting a new one?
Every now and then we tend to forget the real reasons why we do things and have to be given a reminder. This reminder allows us to get our priorities in order and do what’s right. This reminder is also fundamental in maintaining a high level of willpower. Try taking some time aside every day to mediate and remind yourself what you are doing and more importantly the reasons why.