even if you wish to operate as a sole proprietor, you have to set yourself up as a business.
This should not be very difficult to do; don’t be concerned about the process.
Set up a business bank account, pay you, and deposit all of the funds into the business bank account. Pay all of your fitness related expenses out of the same account. File a schedule C on your tax return (independent contractor income / expenses). Drawback: As a sole proprietor without a corporate structure, if anyone gets hurt and they sue you, they can sue you personally, for everything you own.
Incorporate an LLC (limited liability company) and do your transactions from within the LLC. It takes some expense and effort to set up, and as a separate legal entity it needs its own tax return and the shareholder (you) gets a K-1 to include the income on you rown return. So there’s some work to it. But, if you get sued, all they can take are the assets of the corporation.
I’m not a lawyer, and this is not intended to be individual legal advice. I am, however, a former tax accountant so that part I’m very confident about!
After owning two companies, I will advise you to create an LLC and then operate under that company. Yes, it will take some effort to do it and very little capital. If you can consult a lawyer or an accountant that would be the best way to go about it. You will also be able to expense all of your expenses associated with running a business (including mileage, gas, clothes, certification fees, liability insurance, etc.).
I agree with the others and would set up an LLC. As Nancy has explained (and described very well), it takes some effort, but it is worth it for many reasons. I set up an LLC about two years ago and it runs smoothly and was not that difficult of a process. In addition, I think it helps to establish you professionally.
Good luck to you in your ventures!