Taking care of my mom is hard. She's like a grown up toddler. And every time someone asks me how I'm doing I always say, Oh I'm sure others have it much harder. But I really am having a hard time. Why do I not take the credit for what I'm doing...Alone, as my three brothers do nothing. When I'm told I'm doing good, I seem to shrug it off. Am I ever doing enough? Seems silly but it bothers me.
I read books about raising kids, and they suggest that you don't say, "You did a great job" but say, "Look at how clean the floor is. You swept up every bit of dirt. You kept working til the job was done." Specific and factual praise.
"Thank you. It is a hard job, and sometimes (always) I feel like I should be doing more. But thank you. And I appreciate your noticing."
Memorize your chosen reply, and practice complimenting yourself and accepting the compliment. I think AA calls that "Fake it until you make it."