Sorry, I didn't realize that you were so young. I'm 45 and years of training and collegiate competition have ruined my knees, so be aware of the wear and tear you're putting on your joints that you'll have to endure for the rest of your life. I had two arthroscopies and patellar tendon debridement surgery and twenty years later I'm in pain every time I walk uphill or take stairs. I found out talking to a guy in a jiujitsu t-shirt in a line at UPS yesterday that Rener Gracie, from whom I once took private lessons in Torrance and who stacked up my upper spine passing my guard and took me out for three months in 2002, suffered a career-ending back injury, and he was phenomenally talented. A local news correspondent here was a jiujitsu champion but she was taken from the sport by injury. Martial arts are dangerous.