That's not gratitude. It might be something you are glad about, and it might seem like a positive thought, but it's not gratitude. Gratitude is not based on looking outward to other circumstances, but rather gives thanks for what is already right in front of you.
When I am thankful that 'at least I'm not starving' or 'at least I'm both my legs are working' or 'at least I don't have cancer' what I am unintentionally saying is that I am happy because I have not suffered those things. Gratitude is something different. It's being happy for what you do have, not being happy that you've avoided something you don't like. Gratitude is not contingent upon things going my way. It doesn't look sideways to see if others have it better or worse than me. It simply looks at what God is already doing, right now, in whatever circumstance I am in.
There's a world of difference between my children saying, "I am thankful that you've cooked us this meal and I appreciate it," and my child saying, "Well, at least it's not fish, that would be even worse!" Yet, we sometimes give thanks unwittingly in just such a manner.