| | Charisma
The most basic thing I can boil charisma down to is that charismatic persons are able to make a lot of people feel good... whether it be by entertaining, teaching, inspiring, leading, etc. Through the way charismatic people express themselves in the world, they are able to become symbols for hope, pride, freedom, confidence or other feel-good things already inside people, therefore, people like them and desire to be around them.
One way to become more charismatic? Think of the people who you label as charismatic, and observe the traits they have, but within yourself. You really are "projecting" those qualities onto them in the first place... you just need to ask and figure out how to connect to those traits and express them yourself.
As for the sexual energy, I can see that. Charismatic people are pretty sexy sometimes, despite their physical appearances. I guess, essentially, being charismatic clearly involves a lot of risk taking and "vitality" ... which I would say are pretty related to strong sexuality, it seems, at least in men.