This is, of course, easier to do the more experience you have, and harder when you are just starting out - whether it is learning to post, or learning to piaffe, the ability to stay objective and indeed, even laugh at yourself, can help you, your horse and the people around you enjoy THE LONG RUN much more. By keeping some levity in the moment it can also help your mental/physical relaxation, which does make your horse's job easier!
Obviously there are times to be serious and focused, but it is worth remembering that riding is just...riding. I often remind myself when I start getting intense about what I am teaching that world peace will still be elusive, whether or not my student grasps the concept. Remember - walking on a long rein and breathing will never keep you from trying again - and it may make the next try successful for all concerned. My husband Clayton will often ask me if I know a joke - which frustrates me no end when I am being frustated! - but the laugh he pulls out of me I have to admit - makes the moment better. Baby steps to a happy big picture- enjoy your ride!