How to get him to kiss me without being scared

im really scared to kiss my boyfriend, he has big lips and i need some tips on how to kiss him, and when we go out of the lunch room to do it, it always inds up going back to the lunch room bc were to scared. It has been 3 year and we have plaind this for a long time over and over, its always him, we both agree that we want to do it but hes just to scared, im not as scared as he is, but all i need to know it how to get him to not be scared to kiss me and just do it, thanks guys.Edit