Tattoo? :/
Well, it is not something that I support, but anyways I will help you with the language learning :)
The word 'set' has many translations in portuguese, and the word 'yourself' can be or not added in this sentence.
Then you realize there are many ways to say this. A few options to this sentence should be:
O único limite é aquele que você define.
O único limite é aquele que você determina.

I hope it can be helpful :)