Have an external focus. Don't think about what you want, think about what you want to give. This plays into knowing your customer (or whoever you are doing whatever for). Know your customer, and give them what they want. Notice that doesn't mean "create what they want", but understand their goals, and then help them reach their goals.
This is very work focused, but can also play into other parts of your life. Why do you want to be healthy? Maybe so you can be around for your children or parents. Why do you want to be sociable or funny? So you can enjoy your time with your friends, etc etc.
I recently read something that seemed almost nonsensical at first. "Action can precede motivation." In different words it means just start doing the task and the motivation to continue will come to you on it own. I'm sure it doesn't apply to every situation, but I'm finding that there is some truth to it.
This is very work focused, but can also play into other parts of your life. Why do you want to be healthy? Maybe so you can be around for your children or parents. Why do you want to be sociable or funny? So you can enjoy your time with your friends, etc etc.
Externalize the goal.