Excerpt taken from here
Am I smart enough?
That's the wrong question. There is no such thing as ``smart enough''.
If you love playing the piano, play it. You don't expect to be Alfred Brendel or Vladimir Ashkenazy. But you are doing something productive for yourself and those around you. Research is the same. If you enjoy doing it, pursue it. You will usually find that you can contribute something. As you go on, you will discover your strengths and find you have something unique to offer. Maybe there are others who are smarter in some way; they can compute complex probabilities in their head faster than you can, or whatever. But your contributions may be valuable in other ways.
As discussed above, research has many components. Problem solving, identifying issues, presentation, modeling, and criticism are amongst them. See what aspects best suit your abilities and personality. There is probably a niche for you somewhere.
What is written above about kidding yourself does NOT refer to ability or perception of ability; it refers to motivation and honesty about motivation. I want to be sure you are pursuing research for the ``right'' reasons.