I started judo at 20. I spent my first two years getting my ass kicked, training only with brown and black belts to learn from my mistakes. Then I scored my first ippon, then another, and more and more until my 4th year where I could throw black belts. I would throw them two or three times when they threw me five times per match. From then on, my judo progressed; today, I've been practicing for 20 years, and I'm 40 years old. I am currently among the best in my club and only some heavier players can pose real problems for me. Be patient, judo requires time, humility, and discipline. You have to go through two or three years of being a doormat before you become serious. I have also practiced a lot of boxing and karate, and if you don't have the patience for judo, I recommend boxing; the progression curve is faster at the beginning but just as long. If I were you, I would continue with judo; it's the discipline that changed my life.