This thread is entirely useless and it's easy to realize from the title on the get-go. "Belief" hasn't been associated solely with religion for what I believe to be quite a few centuries now, so saying "I believe" does not necessarily mean you believe in god and has not meant that for, again, what I believe to be quite a few centuries. Maybe if I were in the age of the expansion of the church where it reigns supreme and atheists get killed and butchered, but I think this thread is a few hundred years too late to make an impact - not that it'd have too much of a public to cater to back then, anyway.
You can believe in anything and have faith in several different things that are not related to God or any form of theism. Mike Tyson's personal life is something I would also find hard-pressed to find relevant in this discussion, as in no point whatsoever did you mention belief in that little anecdote.
But that's not even where this thread goes wrong, because you're not talking about belief, you're talking about competition. So the title and the original premise have nothing to do with what follows. The main point of this thread isn't "Belief", it's "You should try to compete with yourself and not with others for you are your best comparison". Or, in what's been popular in Facebook and other social media as a happy-go-lucky one-liner since 2000 and whatever, "Try to become better than what you were yesterday!", "I only try to beat who I was yesterday!", "I only wish to surpass myself every day!", and other corny stuff like that which holds no relevance to belief whatsoever unless you come with the total out of left field argument of "they have to BELIEVE they want to surpass themselves and that they can do it!", which, again, is just naturally already inside the statements and is nothing but repetitive and useless.
Now that we've established that your thread post and your title hold absolutely zero relevance with each other, and that from the beginning that biblical passage there on the top of your post is nothing but useless flavor that does not add to the remainder of the topic at all, there's the question of whether you should even be frowned upon for competing with others. If you compete with others you can still improve regardless and be happy regardless, so long as you do not try to imitate his method of improvement to a fault, as even imitation holds it's merit. Competing against others is natural of the world and absolutely necessary in society whether you want to or not. If you surpass someone that means you've grew and you've surpassed your previous self already - so no matter from what point of view you're looking from, you're improving, and that's the end of it. Regardless of whether you're competing with your previous self or with someone else, as long as you're competing with someone you're tied with or ahead of yourself, your improvement will happen once you surpass it, period.
I don't even know why I'm replying. Probably the fact that your Title and your Post are just so wholly off and unrelated, and to top it off, both wrong, made it a bit hard for me to not read through it without laughing, but alas. I guess it's a common read though, even if it reeks of self-help generic talk which is overused and boring.