"The pool is terrible, but that doesn't have much to do with my record swims. That's all mental attitude"

Mark Spitz is referring to the fact that his record-breaking swims are not necessarily due to the top quality of the pool he is swimming in. He is highlighting the value of having a positive mental attitude when it concerns accomplishing success. He is suggesting that having a great attitude as well as counting on your own is more important than the physical environment you are in. He is saying that also if the pool is not ideal, it does not have to be a barrier to success. He is stressing the relevance of having a solid mental attitude and also counting on yourself in order to achieve success. He is suggesting that having a favorable expectation and also a strong job values is more vital than the physical atmosphere you remain in. He is encouraging people to focus on their mental attitude as well as to count on themselves in order to attain success, despite the atmosphere they remain in.