Getting people to identify you as X is a powerful way of increasing your motivation to do what’s expected of X. That is, (1) signaling that you’re a certain kind of person will cause people to expect you to do certain things which are associated with those signals, and (2) such expectations will act as social pressure for you to conform to those expectations. For example, if you look like an intellectual then people will expect you to be an intellectual. They’ll expect you to have interesting or insightful things to say.

Thus, finding an identity which is associated with being the kind of person that you want to be, and then figuring out how to signal that identity, is a powerful way of getting even more motivation for being that kind of person than you already have.

There’s also the social motivation that comes from feeling like you’re part of a group that you respect, especially if you think of that group as being in conflict with another group. That is: If you feel like you’re part of an in-group, then you get extra social motivation. And if you feel like that in-group is on the side of good fighting against an out-group that’s on the side of evil, then you get extra-extra social motivation. To summarize: If your in-group is internally harmonious, with you playing a certain role for that in-group (which is in harmony with the other roles), and your in-group is externally in conflict with an out-group, then from that combination of harmony and conflict comes an intoxicatingly powerful source of social motivation.