Take more risks.
Lack of sexual confidence can result from lackluster sex because it's the same-old stuff. Zebroff says that going outside a settled routine is a simple way people can instantly feel better about their sexual competencies. This doesn't have to mean introducing the scariest sex toy you can find. Try a new position, have sex in a different room, start with a massage. Change does not have to be extreme to result in a major improvement.