Is saying "You're Welcome" difficult because you don't like giving a highly used, and formulaic response? Is "You're Welcome" difficult because it doesn't really express your sentiment? Does it not seem genuine to you? Can you see more into what the resistance toward using the pro forma "Your Welcome" is?
There are a lot of situations in which an exchange of formulae is just that, and I think that the best thing to do is to go along with a polite exchange fo the formulae. It's sort of a minimal level of social grease to avoid frictions which could make things worse. Similar is a response to "How are you?" Often, it is not asked to find out how you are, but as a formula greeting. In such cases, I return the formula with "Fine thanks, and you?" no matter how I am actually doing. In situations where the other person is actually asking how I'm doing, I'll let them in on it, within the limits of the actual nature of my relationship to the other person.
A "Thank You" can be offered with a very similar range of intent.
I find that a reply which fits the form or intent of the "Thank You" is best.
If the "Thank You" is pro forma, then I reply in kind with a pro forma "You're Welcome", said politely but with a comforable distance. If the "Thank You" is meant more genuinely, then I reply with something similar, but less formulaic like "You are Welcome" (with a bit of feeling) or "It was my pleasure" (with a touch of warmth). For more heartfelt expressions of appreciation I tailor the response to be in kind, within the limits of my actual relationship to the one expressing thanks, with some good-natured humor if there's some comfortable informality with the other person.
For moments when I'm not feeling particularly generous, and I'm not exactly really glad to be offering help, the polite formulaic response can offer a comfortable lower-limit response to at least not offer an occasion for friction with others when I'm not quite up to my usual par. Again, the formulaic expressions we exchange are the oil that helps to keep our interactions with others at a safety net level of civility. The goal is to operate well above that safety net, but there are always those times when the safety net is far better than where we might be without it.
