Don't be afraid to push yourself. You can do more than you think you can and you shouldn't let fear of failure or embarrassment hold you back. To quote the title of an old self help book: feel the fear and do it anyway!
Embarrassment only lasts a minute, but the feeling of accomplishment lasts a lot longer and will keep you going. Don't let embarrassment/shyness/fear prevent you from asking for help if you need it - most people want to help you achieve your goals. The ones that don't are to be pitied!