This is an important point. There is sometimes the confusion that one must achieve great things to feel great. This is often counterproductive, because it can lead to attempting things far out of one's league, and thus produce ego shattering failures. It is easy to understand that abundant failure breeds self loathing. The reverse must be understood to be true as well.
Huge successes are dramatic and can boost self worth a great deal, if briefly.
However the risk of failure is greater, and at the lowest levels of self esteem this becomes critical. Tiny successes may seem too small to be satisfying, but over time they stockpile. Enough tiny successes can create sufficient confidence and self knowledge to make larger action successful. Even if one diligently applies all of the concepts above, it can come to naught if the drain of the environment is too great. Other beings are our mirrors, they reflect to us what and who we are by the effect we have upon them.