Sounds like you're doing a great job already. Well done.
Based on the continuous increase in growth, and assuming that there is a growing market for your product, it shouldn't be too difficult to find an investor.
What you would need is to create 2 investor pitch decks (presentations): one which you use when presenting in front of them, and one which you send to them (they are similar but not the same). The pitch deck that you send to them needs to be perfect as you only have one chance.
There are a lot of lists available of investors. It depends which country you're located in and where your target market is.
I've successfully helped over 300 entrepreneurs and would be happy to help you if you need. After scheduling a call, be sure to please send me some background information so that I can prepare before - thus giving you maximum value for your money during the call itself.

Assaf Ben-David is right with what you need to do, but before going there you should know what you expect from an investor. Are you just wanting the money? Do you hope that they'll have the expertise to grow your business? What are you going to do with the money?

I also agree with Assaf Ben-David that it sounds like your doing well. Also, before getting ready for faster growth, make sure you are scaleable. I check this with every company I have worked with because if you don't put the pieces in place to be scaleable, it could cost you more than you gain.

So before trying to find an investor, figure out why you want investors, what you expect to get from them and are you scaleable. Plus, make sure you have a sales process. Putting in a sales process alone, will accelerate your sales tremendously. When I did this for a client, they grew and additional 33%.

Hi,
It's great that you are considering additional funding. The best way to find the right investor is to network in the fitness industry. Attend events that are relevant and where investors are likely to show up, such as Pitch competitions, startup events, investor dinners etc.
It's also important to choose the right investor - and not the first one that offers you money. Make sure you have at least 2-3 offers before you make a decision.
I hope it helps!
Sara