Don’t know why!

Today, I have this sadness inside me. Seriously speaking nothing bad actually happened to me but I don’t know why I feel a bit low today. The day was tiresome for sure.
This happens with me many times. I get sad for no particular reason. Nothing seems right, something seems to be missing, its like something was supposed to happen but its didn’t and I don’t even know what that something is! I have had better days. I even don’t know what is troubling me! Its just not my day i guess.
May be it is in my mind. I think I am sad and therefore I am. May be what I actually need is a friend to cheer me up!