Lust awakens and the protagonist must use the Jedi Force to stop it. To do this, he will need sexual relations with other girls, and since his body is not capable of this, he uses the Force to increase his sexual energy. Actually this is not true. His strength doesn't increase, he just can use it for other things. The power of a Jedi is the power he uses. This is the power that is used to change situations that affect his life. In that sense, it is not physical, as it is only the ability to use it in this life, not the ability to create something out of nothing.