How to become flexible again?

When I was in junior high, coaches were more strict and we were required to stretch everyday. Of course there were slackers that pretended to stretch, but I was sure as hell I wouldn't be one. Anyway, three years of stretching paid off and I was able to grab my ankles and lay my head on my knees with my legs straight. Of course I could reach past my toes, but not to the extent where I could easily place my forehead on my knees unless I was grabbing my ankles. That wasover two years ago when I was 14. I guess I quit stretchof because I lost my motivators which were my coaches, I know it's not a valid excuse, but I lost my daily routine. In high school pe the coaches dont give a crap whether ypu do anythomg in the cl, but dressing out unless youre in athletics. Now that I'm 16, turning 17 in 5 months, I yearn to gain that level of flexibility again. At the moment I'm capable of reaching past my toes and holding my hands there for atleast 60 seonds if not more. In jr hs pe we just held it for 10 seconds. I was thinking if I could accelerate the process and be able to reach my knees within 6 months or so of I stretched for 60 seconds instead of 10. Are there any cles I should take? I hear yoga is good, what about taichi or wushu?