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.
"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."
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.