If gravity does not effect you and even has an opposite effect then you could hold anything in the air without effort. If you carry a person on your back as you fly, both of your weight combines and since gravity has an opposite effect on you the gravity of the person you are sporting on your back is negated and that person is weightless as well. think of that but with cars, large animals, buildings, or even other planets. if any weight is added to you during flight, then the gravity that causes that weight is also negated. Example: let's say if Mars is in a collision course with earth, each planet's gravity creates a repelling force on the other planet through your power. The double opposing gravitational forces from Mars and Earth get amplified and repelled from each other and the collision is stopped.
think of two magnets, if you put the north side of one magnet to the north side of the other magnet they repel each other. that is what happens to you. each magnet is the planet and the repelling magnetic fields is you.