Usually when that happens to me, I try to focus on something other than transition that I enjoy... such as one of my hobbies or talents. Something that occupies the mind in a positive way.
Sometimes it is so easy to forget who you really are and get lost in a sea of dysphoria.. with all concentrations pointed toward outward appearance. It's a double edged sword, in my opinion.
I have always thought moderation is the key for myself, but also having moderation with that moderation itself. Sometimes it can be necessary to follow down a path driven by obsession; the mental drive you get from it is one of the strongest of all and can take you to great heights. It can be very hard to know the difference. Generally, I try to seek happiness. And, if I'm able to stay focused on that, it generally works.