You can't please everyone. Don't worry about him.
You just do you. He's responsible for himself.
Let him be annoyed. That's his choice.

Maybe he thinks you're full of yourself? Narcissistic? Like Trump going on about how great he thinks himself to be?

Just keep repeating the phrases "I'm awesome", "I'm great", "I have a very large a-brain", "I'm the best", "Everybody loves me", "I'm a genius...a very stable genius" etc. One day you may even get to be president.
How could that possibly be annoying?

Some people are just negative and simply can't abide a positive person. Ignore negative people. Sometimes they lose their charge and just fade away
My favorite is that I'm doing so good the whole world has a right to be jealous of me.

Awesome is an over used term and usually used mistakenly.

Don’t worry about the one guy. It might not have anything to do with you. Maybe he does not like the awesome or maybe you remind him of his sister. You have no control over him and his reaction. Just live your life and be awesome!

stats determined that on average about 30% of people around you dislike you for no tangible reason. He's projecting his miserable life on to you. Ignore and pass on.

I think you are fine and the guy is just not into you. Tell him to smile, it makes him look much prettier. (Just kidding!) The only thing to think about is your working relationship. When you do something awesomely, is there any chance he could perceive himself as having a role in that that you are not recognizing? If the answer is no, then it is all on him. Carry on.

He's a nincompoop. You're awesome. Don't you ever let anyone bring you down. You sound like fun to me. ??

If it does annoy him ,good manners would prevent him from stating his feelings.Most people from time to time think of themselves as awesome,but their personality type will dictate if they actually verbalize their feelings.

There's a fuzzy line between bolstering your self esteem with self congratulations and conceit. Make sure that you don't congratulate yourself more often than you congratulate others, especially the fellow who seemingly is bothered by your occasional self-pep rallies.

We all need positive reinforcement, and should take care of ourselves that way. For those with low self esteem, seeing others do it can either be a positive suggestion that they should do the same, or could be a reminder of their own self doubt and shortcomings, and therefore annoying.

Maybe try to be understanding how your words might affect others, and what their mindset might be, if you can get to know what that night be.

I spend time uselessly trying to figure out people too. Maybe his ex wife did that.

Sounds like and uptight individual. You be you.

I tell people I'm fine as frog hairs spilt four way and sandpapered. Some people just don't get it and those are the people Ignore!

Before you ask yourself why it bothers him so much, ask yourself why you care.

What is the context? Is this man your peer, your manager, or a subordinate? What kind of work do you do?

I'm usually the manager so if I went around telling everyone how awesome I am, I would come across as a conceited asshole. If I went around within my team and said how awesome the team was, that would be fine.

Context is everything.

His problem, not yours...you can be even more awesome by not letting the opinions of other bother you...there is nothing that you are doing that is hurtful or disrespectful to him or others...I agree..be awesome!!!

I understand him, but I don't think you need to worry about it.

He's annoyed at his own inability to tell when you are sincerely awed. Though I would likely share this difficulty, I say it is not your problem.

I also hate cheerful morning people and certain sounds people make naturally .... Again, not their problem, all mine!

When I get that from people, I put it down as jealousy. They see you happy and don't understand why they don't feel that way about themselves.

I'm going to let my autism show for a minute.

when someone says consistently that they're awesome, or the like, to me that means that they believe that they have completed their ability to grow and incorporate new information. I think that curiosity requires humility, to acknowledge that there are things that we don't know or are able to do.

When you say that you're awesome, it sounds to like you think you've got it all figured out. And I don't think anyone has it all figured out.

How do you know it’s that phrase that bugs him? Maybe it’s the volume of your voice when you get excited? Or maybe you say it so often it grates on his nerves. Only way to know is to ask him.

I can identify with getting slightly annoyed if a certain word or phrase is overused all the time but Im also guilty of getting stuck on certain vocal tics like that in the past. He's more than likely just projecting and crabby that he doesnt feel as positively about himself as you do. Maybe try finding a few optional ways to put it, but I wouldn't worry too much about it.

I'm envious that your instinct is to repeatedly support yourself. I mostly just repeatedly sigh and think "I just wanna die." Which is a big improvement over 2016's mantra of "I wanna kill myself." It's seldomly if ever been literally true, that's just the feeling that tends to wash over me from time to time. I do think Im awesome as well. It's just that the interjector in me is mostly disappointed that I have so little to show for it. Keep bein positive, people like me and mr crabby pants can only aspire to be as awesome by default as you!

Why worry about it. To be crude, fuck him if he can’t take a joke.

I personally detest the over use of that word. It should be used to describe things like the birth of a child, the Taj Mahal, Grand canyon or the milky way on a cloudless night. Not a friggin pizza! To wit I even wrote a satirical song about it using rhymes such as Nigella Lawson, sore thumbs and foursome with your mum.
This is not to belittle your success at work or your good self but perhaps you could find some other words less all encompassing to describe them. Such as outstanding, vibrant, remarkable, lovely, victorious, virtuous, diligent, tenacious, brilliant or even orwellian newspeak double-plus-good.