The most essential constituent in a person's life is confidence.
The inevitability of something detrimental happening when one is feeling the most confident in himself cannot be escaped. The very perspective subjectivity of how one performs is impossible to be circumnavigated around. You could be epitome of excellence in one field yet some people will still find you 'just okay'. The way to get out of this paradigm is to stop keeping expectations with other people. The world is meant to disappoint, it's just how it works.
One should only keep expectations with his own self. So even disappointment gives motivation as a by-product. It acts as a perpetual stimulus to better oneself. Try to keep your goals as high as possible even if they seem far fetched. Work as hard as it is required to reach such goals. Be over ambitious. Because even if you don't land up achieving it, but will reach near enough to keep you contented.