This was written for someone specific, but you might find it true for you also:
Have you ever demonstrated that you are smart? Ever passed a difficult test? Have you ever made good decisions in your life? If the answer is “yes” to any of these, then you are smart.
We all have our failures — failed dreams, relationships, tests, etc. Even the smartest people we know have had such failures. We can’t measure our intelligence based on our failures or our short-comings. We have to base it on our wins — our successes.
And don’t compare yourself to others. Otherwise you will always feel like you’re not smart enough, because there will always be someone smarter than you, even if just for a brief time.
You have to look back at your own track record — your own success. This way you will be reminded that you are where you are today because of how smart you’ve been. Keep building on the foundation you’ve laid and don’t give up, you are getting better.
There’s no doubt that you are smart. The question is: will you keep applying yourself the way that you have been? Part of being smart is continuing to move forward even when you have doubts about your abilities. Part of being smart is working hard at the task at hand, willing to put in the time and effort needed to get the results you want.
Anything that you might lack in natural ability to retain information or understand complexities can be made up for through persistence. Keep believing in yourself and the path God has laid out for you.