While we need to carry out our duty to the best of our abilities, always remember that you don't control the outcome of events. Even the Prophets did not control the outcome of their efforts. Some were successful, others were not. Once you have done your duty, leave the results to Allah. Regardless of the results of your efforts, you will be rewarded for the part you have played.
However, never underestimate your abilities. Understand the concept of Barakah (blessings from Allah) and remember that Allah can and Insha Allah will expand them if you are sincerely exerting your energies for the right path.