Writing a goal down and adding a deadline to it is a form of motivation, but sharing your goal with at least one other person increases the likelihood of you following through. It adds social expectations of you achieving that goal, and you will be more likely to work away at it if you know others are keeping tabs on you.
Write this goal down.
Add a deadline to it.
Share it with at least one person.
You can even post it online!
Identify one person who will check in regularly and hold you accountable for staying active.
It could be a friend, a coach, or a personal trainer.