Taking it one day at a time
Don't feel guilty if you can't come up to the standards set by others for you! You set your standards! Only you know how you feel! Learn to say no when it's necessary, and do not let anyone make you feel guilty for doing so!
It is also essential that you care for your Addison's with adequate steroid cover, sufficient salt and fluids for the day...sometimes this requires lots of planning and invention! But you can do it! My water bottle and I are rarely separated for long! I carry extra steroid and medicines that just might be necessary to prevent a crisis...and never be without your emergency injection.
Remember you are a useful human being who just happens to have Addison's Disease.