I used to have this problem. To address it I practiced mindfulness whenever I noticed I was hurrying or tense. I did whatever I was doing, but very mindfully--feeling and noticing every step I took, or what I touched, etc. It's almost like doing something in slow motion, but with deliberateness and your full attention, being fully present and non-judgmental. After awhile the habit of hurrying and tension went away. Occasionally it resurfaces when I'm stressed, but I just go back to being mindful for a few minutes and it goes away.