Loneliness. Loneliness is one of the major causes of feeling overwhelmed by sadness. I feel as though when you are all by yourself and you feel down, you make it worse by just thinking negative thoughts constantly without having any positive energy to lift your spirits. You eat at your own negativity, pushing more and more negativity into your brain for it to digest. It's poison.
You're killing yourself. You need to get out there.
I know it's going to be hard. It's going to take every fiber of your being to finally leave your bedroom or dorm room to go out into the world, but you have to do it! You need to go outside, look at the grass, the trees, just breathe it all in. You need to meet up with your family and friends. Being around people who love you will help you overcome the sadness that dwells within. Their happiness will seep into you as you make happy memories with the people who truly care about you.
It becomes easier as time goes on. Now, whenever I feel like the negativity within me is getting overwhelming, I'll go find my friends, I will usually explain to them how I feel, but even if I don't, just being in their presence and laughing and doing fun things with them keeps the negative monster within me at bay.
The key to overcoming loneliness is to realize that it is the cause of the negativity you are feeling. It's frustrating when you constantly have a heavy heart and all you can think about is how many things are wrong with you or how no one likes you. Once you realize that you're feeling alone, you need to make the active effort to meet people who do love you and who do want you. Being around them will allow you to realize that you were wrong to think no one wanted you. You will get to see how dear you are to the many people who do love you.
You must remember that you and only you have the power to help yourself. If you feel that you need the help to get started on your journey, you need to go get it, and then you need to use what you were advised to become the best version of yourself. A happier version.