OK, spa day. Think, and think again, that these masseurs/euses have seen it all. Think of very old crinky skin, people farting (happens a lot as you relax), people who don't wash... honestly, my friend is a masseuse and she says that like a doctor, she couldn't care less about the body itself, she knew they would come in all form and shapes when she trained, and as a matter of fact, she says that massaging someone with more fat is more enjoyable to her. Discuss the products and make it clear you are allergic, they are used to this.
Body conscious because of the others there? Who cares about them. Honestly, if you let it, you can really make it an enjoyable experience.
Flying, well I'm totally with you on that one as I have a total phobia that has been there for 20 years. I didn't fly for 10 years until I met my OH. We both love travelling and always wanted to see other places, so I had to tackle that flying issue. I cannot tell you all the stories we have of my flying experience... from almost not getting on a plane because I overdid the drink before (I never drink!) to saying inappropriate things (nothing rude and taken well, but still embarrassing afterwards) to bursting in tears getting on the plane in front of everyone. I'm doing it though, with help of some magic pills and it's got less bad each time. I've even done long hauls. Ironically, I'm flying in a few hours, had the usual nightmares before, really really don't want to, but I know I'll be ok and it will be sooooo worth it when I get there. I can't imagine ever enjoying flying, or being relaxed, but I care get to the point of bearing it and that will do. You can do it!