What are mental formations? How do we work with them in meditation and asana practice?

To me, mental formations are our personal roadblocks. They are the stories that I create in my head which convince me if I can or can't do something. They play a huge component when I'm doing unkind things to myself, like self sabotage. When I'm working with my (mental health) clients, I call them self fulfilling prophecies. I think they encompass a broader scope than that though. Mental formations may also start out on a positive note (as in being in love in a new relationship) and soon these feelings of love can slowly start to spin out of control and within two weeks you have already planned your wedding and named your children and sent them off to university. When he failed to return your phone call after your second date.

Either way, mental formations lead to suffering, which is something we want to be free from in our lives.

In meditation and asana practice I observe them when they start, and I encourage my students to do the same. If I feel my mind spinning out of control I try to redirect and return to my breath. Sometimes I can. Sometimes I can't. Sometimes I do feel the need to let them spin out of control because that in and of itself detoxifies my mind. I don't know... I guess sometimes I feel that if I just observe and notice and go back to my breath I end up burying feelings and emotion? I don't want to do that, because when I do, I feel like I'll explode. And that's not pretty.