How to stop this

I always make plans or have a party or something and I’m hype and keen for it and then the time comes to leave and I 9 times out of 10 back out and don’t go. It’s like I just am not in the mood and just feel like I want to cry (?) but for no reason.

It even happened for MY OWN party. I didn’t wanna go, I dreaded it until I aas there. But I’ve just backed out again on going out with my friends because I just don’t feel up for it.

What do I do?