Question 006: Street freeze

I am currently 1st dan WTF and train 3 times a week (mainly sparring) and I used to fight at national level but now I just fight in the occasional kickboxing fight (because its easier). But in the past few of years (regrettably) I have been involved in a couple of fights in the street and I seem to freeze in the initial confrontation and took a couple of blows before reacting. I fought back but with not much enthusiasm. I don’t know why this happens because when I am in the ring I am confident and very aggressive. Yet in the street, I freeze, and after the fight, I beat myself up for not defending myself properly. Any idea why this happens and any tips on how to deal with it?