I was never "in". I married someone with family and friends that were in.
The best motivation comes from within. THe desire to do the best you can with what you have. That is just my way of doing things and it works for me (but not everyone). Pick some easy to attain goals, make a plan to get there, and do it. Set higher goals and keep going. Eventually it becomes habit and ingrained. Just do not get discouraged if you fall short once in a while, especially with very ambitious goals.
I have a family member that only gets motivation from trying to be the person he thinks others want him to be. This worked for short periods, but always required others around him to keep him 'in line'. People got tired of this responsibility and when they left, he just fell into the worst he could be. He still has no motivation and does absolutely nothing to put his life together or mend relationships with the family he drove away. He is the way on the far end of the lack of motivation spectrum.