I'm 40 and have been challenged by flexibility issues since I began martial arts training in my 20's. It's only just recently that I'm finding really effective ways to improve. I can tell you what's worked for me but the key thing is you have to be aware of your own particular issues and how you address them. 1. Stretching isn't enough, it's how you stretch that counts. Don't go in too deep too fast, and make sure you breathe through your stretch. Often during in-class warmups it's impossible to get a good, productive stretch - things are just too rushed. Take some time on your own to stretch your tight muscles mindfully. Find that point where the stretching sensation transitions into pain and back off a bit. Stay there and play with your body position & breath to make sure you're relaxed & have good structure. Don't just do a stretch, know it in all its phases. 2. One cause of chronic muscle tightness can be chronic weakness in antagonistic muscles. I saw this all the time when I was a massage therapist. In my case as a karateka, I think my tight adductors (groin muscles) are worsened by weak abductors (muscles that raise the leg out to the side. As I've worked on strengthening the abducotrs, my flexibility in getting my legs apart is improving. Remember, the body keeps muscles tight protectively if it senses that it's moving into an unstable/potentially dangerous position. So by increasing your overall strength & stability, you create the conditions for your body to open up more. 3. Keep at it. To really change your flexibility requires discipline & patience, but you can do it. And in the meantime, keep kicking & working on your technique. Though my static flexibility is still relatively poor, I can maegeri to the level of my own chin, and mawashigeri to the level of my ribs, easily.