1. If you want to be fit, you have to exercise really, really hard every single day. - No, not every single day, but you do need to train hard consistently.
2. Carbs and sugar make you fat - Absolutely false.
3. If you are not sore after a workout, you didn't work hard enough. - False.
4. If you want a six pack, you have to do more ab exercises - Couldn't be further from the truth.
5. You need a gym membership to get fit - This makes no sense, completely false.
6. If you want to lose under arm fat then you have to do tricep exercises - Lifting weights is indeed necessary, but diet and genetics, plus age play a big role. Can get as much benefit out of compound movements like bench, shoulder press and pulldowns but adding isolation exercises certainly can't hurt.
7. Your body needs to be cleansed or detoxified - Can't really comment. Depends on you daily diet. I like doing IF which in a way is a little bit of that sort of thing.
8. Strength training will make you bulky - Trust me, this is false.
9. Sweating more means you burn more calories - False.
10. You have to eat protein 30 minutes after a workout - You don't have to, no IMO. But protein needs to be consumed in a higher than normal fashion daily.
11. You have to cut out fast food if you want to lose weight - Definitely not.