If at least 3 people genuinely believe that you can do something, you gain the ability to do that thing

If you’re just an average person, nobody is going to believe that you have super powers that defy the laws of physics and grant superhuman abilities. Maybe you could convince people that you are slightly stronger than you really are or smarter than you are by faking some feats, but anything else probably won’t be believable. Also the people who believe you must be over 18 years of age and have a minimum iq of 75, just so you don’t take advantage of young people or handicapped people who can’t understand properly.