"They can have that opinion of me if they want to; there's nothing I can do about it. They have a right to their opinion." I've often applied this school of thought to negative opinions others have had about me. What if we applied that thinking to the positive opinions others have about us?
Sadly, most of us have a friend or two who have so many positive traits and yet canNOT take a compliment. Maybe even you are that person? As a performer I've learned that nobody who gives you a compliment wants to hear in return a list of why you don't deserve it. I used to smile and say thank you even though I didn’t feel the happiness the compliment was intended to bring me. I read something one day, however, that completely changed my way of thinking. Ponder on this--
"The woman who deems herself unbeautiful makes a decision for me that I would rather make for myself: She has decided what I should find appealing. Not only that, but she also levels a harsh judgment against me: that I don't have the ability and the powers of perception to see her more deeply than, say, the camera's viewfinder." (Always Hit on the Wingman . . . and 9 Other Secret Rules for Getting the Love Life You Wantby Jake, Glamour's male dating columnist)
Alright, now read that again. Let it sink in.
Essentially, he's saying that whether or not he thinks your beautiful is his decision, and his decision alone. And there's nothing you can do about it.

Do you think the person giving the compliment was just deluded?
I bet if that same person had given you needed advice, you might not have brushed them off so quickly.
Do you really think he or she was lying to you?
So, why did you brush off that compliment?
If that person isn't lying or deluded, your only other option is to take them seriously.
I get it, accepting and internalizing compliments can be scary. I get that fear of not wanting others to think I'm full of myself. Do you really think a genuine, "Thank you!" and smile will give off that air? It won't, I promise you. And until you can follow up that genuine thank you and a smile with a warm, fuzzy, mental self-hug, follow it up with a heartfelt thanks to God for sending someone who sees in you a little of what He does.
Even if you "deem yourself unbeautiful" at some point this week, tough luck. I deem you beautiful, and there's nothing you can do about it! :)
Grace