Stretching should help a ton. I stretched a few times a day for a few weeks and I became much more flexible. I was just doing the normal stretches that you would do to warmup to play a sport or train, but I would do it for a bit longer than normal.
If you are more lean then you will be able to become more flexible than if you are packed with muscle as well.
The 2014 Hit Squad (FFL)
Eddie Alvarez - Junior Dos Santos - Patricio Freire - Jessica Eye - Pat Curran