Have you tried throwing your bicycle as far as you can? I got about 20 ft. out of a pretty heavy mountain bike after some tire-changing issues, and it worked for me. I figure the adrenaline gave me some extra strength and focus. (Ah, I see the river comment -- commit to this impulse.)

Can I suggest changing other tires? That is, a kid's bike, an old beater, etc. Some experience finishing the job will most likely open your eyes to tricks or approaches that you could apply to a much more difficult tire and rim setup. (This is 'the knack' someone upthread mentioned.) I also suggest watching the mechanic who does change your tire, and maybe asking them to undo it and let you redo it.

BTW donuts and six-packs are good ways to sidestep any bike mechanic embarrassment issues.