nerves getting the better of me

so I have had the opportunity to meet a few people lately for a coffee at first but I have lost my nerve at the last minute and cancelled. the guys I have let down have been understanding - well at the moment anyway. how do I overcome my nerves. I am so comfortable at home when I am on my own but in public, well to meet specific people, its a different matter. I am not body conscious although I would like to tone up a bit more but that's for me... I don't mind seeing other people nude so that's not it.. so why do I bottle it all the time??I think I should just go to a beach or forest walk or something by myself and see how I feel, if I get chatting to some one then hey that would be a good step....yes that's it - by myself first.