For Great Justice...
Your power is: Super Strength
Explanation: Your gift is rather self-explanatory. You have been given a power that makes you extremely strong--speaking, of course, in physical terms. When doing good deeds, the power could be used to help people in fights, rescue those under a fallen building, etc. For bad purposes the power could simply kill/beat anyone until the gifted gets his way.
Positive Aspects: You are, however, a person on the good side. You are the leader type and have a tendency to look at the whole picture rather than details. That could make you come off as inconsiderate, but that's far from the truth. You can be impulsive and aggressive but you mean no harm with it. Sometimes it can even save you. If you were in a group with others who have super powers, you would focus more on them and the situation rather than yourself. So to even it out, you can be egotistical at times, but it's because you ignore your needs every once in a while. You are responsible and brave but could still be seen as reckless.
Negative Aspects: Since you focus on the team/family/group of friends, you could start thinking that they don't care about you since they don't seem to look after you the way you do them. You could unintentionally endanger yourself (even in everyday life) when acting without thinking decisions through first. But, with experience, you can become a leader with a sense of responsibility who comes off not as reckless, but logical.