Not sexually attracted?

So I'm sure I'm not the only one but does anyone else not enjoy sex? Like at all? I love my boyfriend but I'm not sexually attracted to him... or anyone for that matter, never have been. I don't enjoy sex at all, I don't like being physical at all for the most part, but I don't want him to know that, I don't want him to think its something to do with him because it isn't. I don't know if there's something wrong with me or...?? Does anyone else feel like this? Any advice?