Depression is related with heart. In another word, if your heart does not feel good, then it is easy for you to feel depressed.
One easy way to check: lie down on your back and draw a line between your two nipples and then find the middle point. Massage the middle point, you should feel pain there.
The other way to check is to massage your under arms, you will also feel pain.
Spring is coming. A lot of people will feel bad, feel depressed.