This applies most of the time for most people, but there is a subset of people that can not control their attitude due to a mental disorder. One example, depression is a hell of a thing and still so misunderstood. For someone that has been there, I’ll tell ya there is absolutely no control over the inner voice and trying to positive talk yourself makes you feel even worse because at the time it feels like more pathetic BS. Sometimes people are just stuck with a bad time with a bad attitude. Not trying to demean the quote for most, but it’s nonsense for someone in that situation.