Stand up straight, wear platform shoes, and think of some role
models who accomplished a lot without being tall (e.g., Sammy
Davis Jr. and R. Buckminster Fuller off the top of my
head). Although it won't make you taller, consider working out at
the gym to bulk up a little. Not everybody your height feels
self-conscious about it, so maybe some particular person or event
in your past has made you feel that way. If so, then figure out
what it is and deconstruct it.