u/No-Locksmiths

I'm thinking of changing careers and becoming a personal trainer. I'm thinking of working at a big box gym. I'm a single woman with no kids or pets so I can live off a lower salary. There's a technical college where I live that has a health and fitness associates degree. Would I be over qualifying myself? Are the online certificates enough? I know how to exercise my own body, but I know that everybody has different fitness needs. I don't want to accidentally hurt someone. Can anyone help?