Can you actually have a lot on your mind?
Of course it sometimes feels that way, but, where is your mind? What is physically resting on top of it, or, cramming into it?
Nothing of course, other than thoughts.
Thoughts are real, and powerful.
But they are not physically heavy (though they may feel that way). You cannot actually weigh them on a scale.
Thought is very powerful, in fact, I am probably more in tune with this than most average people, meaning that I believe the thoughts which you repeat, concentrate, and focus on will definitely manifest in the physical world, which, might be seen as slightly unconventional.
But even with that said, it is sometimes helpful to remember that if you have a lot on your mind, you also have to power to dispel those thoughts and make them disappear like smoke, as they are nothing solid.
Unless you make them so.