What Makes You Insecure?

What makes you insecure? I really want answers because lately I've been unbelievably insecure and for stupid reasons. I just look at a girl who is beautiful and I want to shrink into the ground. How Do you get over that? Honestly it could have to do with my guy friends pointing out every hot girl they see and it could be caused by stress from losing a lover, a friend, and family members. Please tell me what's you're insecurity and how you get over it. If you don't want to leave it as a comment you can message me also.