"The word talent is but a lie. There is nothing called talent. There's just people who believe in themselves and those who don't."
Okay, before I start boring you out with the "lecture", let's just sit back for a while and play a game. Take a paper and pen...
Done? No? What's wrong with you? I'm serious. I give you another paragraph change, go get a pen and paper.
Are you back? Good. Now, list 5 things in life where you have been a total screw-up (for example, Academics, Relationships, Love, Confidence). You can write more if you can think of more such things. After you're done, cross out those things that you believe are NOT absolutely necessary for your survival in this big, bad world. For example, you can very well be a rich and powerful person even if you're not a particularly confident person (so you can cross it out of your list).
Now that half of the picture is clear, start listing those things which you are good at. And they don't have to be universal constants like singing, dancing, acting, painting. You believe that you are a people's person, one who can handle nasty situations with wit and intelligence? Add that to the list! Okay, you don't know how to cook but make a mean Pasta? Good, add that too. Every little detail is important. Add every single thing that has ever earned you praise from your friends, your parents, your neighbours, things that have been mentioned with your name because somebody out there believes that you are "good" at them.
I think you know what the next step of this exercise is. Take your list and compare the two sides. The pros against the cons, the weaknesses against the strengths. Oh, and please don't add weight to the attributes you are comparing. "Academics" is more important than being good at "making a rangoli" should not feature in your comparison. In your list, every trait is equal, the relevance of any of those traits is not something to think about.
Do you see what happened here? The number of things you are good at beats the number of things you totally suck at. You might deny this entire exercise due to the fact that we very systematically limited our critical angle on things that you are not good in, and placed extreme emphasis on the things that you do well. So, I will, very vaguely, quote something from the last episode of the superhit American series True Detective - "technically speaking, there is more darkness in the universe and all the stars are just tiny dots scattered in the vast blackness". There will always be more darkness, but life is all about holding on to the little trickles of light.
So, yes, being an average student might give you the feeling that you are hopeless and talentless. But there is more to you than you give yourself credit for. What makes you average is not your modest skill-set, it is your attitude towards yourself.
We are now at the final step of this exercise. Turn your clock backwards and try to remember the last time you said - "I wish I was as talented as _____". Now remind yourself this, the person who fills this blank was not born talented. Okay, maybe she (or he) was. But Albert Einstein alone did not take the world into the 21st century. Just like there are different kinds of people, there are different kinds of talent. And you don't need to be an expert at something right away to call yourself talented.
So, that is the moral of the story. Talent is not what you carry in your genes, it is what you do with what you have. You are born into a society that sits at the pinnacle of millions of years of evolution, that in itself is a talent. I don't believe you need any more. What you need is self-belief and the passion of wasting your time on doing things you are good at.