In the last month I went out maybe 5 or 6 times only. For me the factors are: the weather, currently not working, depression, social anxiety, and being alone. I can force myself to go out, but more often than not when I do so, I go back home disappointed and more depressed. It's not a way to live, but being alone can throw you in despair. You cannot do things alone. I mean, technically you can, but you feel you are being judged because of that. Also, you feel bad about yourself that every body else is with someone but you. If you are sociable, maybe make friends or go to meeting groups, or if you already have friends go out with them every once a while.