A burden is something that weighs you down or just stopping you from moving anywhere further than where you are now. An object that no one would wish to be equipped with, pair up or even anywhere near to it. A good for nothing item. A worthless unwanted person.

To people, they have a list of standards you have to reach in order to be good enough for them. Like how the human mind prefers you to have an eye-catching appearance. Not too fat, not too skinny, not too short not too tall or even too ugly. No matter whether or not that person has any good sort of talents at all! Then there're skills. Do you have the skill they require you to have in order for them to achieve their goal with? And if you do not have any of those requirements you are deemed worthless.

They would never even thought of the fact that if you try hard enough even an old man can move a mountain. If you try hard enough you can change something you are not genetically born with. You can overpower your own burden and drag it along with you. 

Then again human mind never changes and maybe it will always remain the same. Once you are label as a burden. You shall always be a burden. No matter how bright you try to shine. A lump of coal that under pressure can become a diamond. But a diamond that always has dirt tarnish it.

'they tell you to be yourself and then they judge you'