Dreaming of flying interpretation ?

Ever since I can remember I have always had dreams where im flying. From the time I was a little kid and im 27 now I have them at least once a week. Usually im not just soaring through the air, but sometimes. Usually im around friends hanging out in my dreams and I start floating up and come back down and its like I have to concentrate hard to stay afloat. Alot of the time i'll be playing basketball and all of the sudden I start jumping really high and doing crazy dunks and float around. What does this mean?