You love the feeling of adrenaline so much that when in battle or outside battle that even the thought of getting hurt or killing someone gives you a bit of adrenaline

The max speed you can cap at is plus 20 or 30 depending on dm's discretion. Per encounter and outside encounter resets after encounter

Because adrenaline your senses are heighten when you roll for initiative you get a plus 1 to every roll

When any one in your party gets a natural crit in any way even outside battle you get a plus 1 to your speed

When you kill an enemy by any means you will get a plus 1 to your speed 

Getting hit by any means Gives a plus 1 to your speed