4cfed, u not old, u never old to run... who told u that? shape? go do some running, 10miles per week running, in a month u start gettin good shape...
tecnic for running, theres a lot, but just to start try not to over throttle on jumps, is better end, then have to stop wit a broken leg, lol... once u learn the posibility of ur landing n throttle u can start jumping even more n more, but not allways necesary a big jump...
learn the whoops tecnique, this is important, and not hard to learn...
learn how where and when u do put ur weight, set the gravity spot so u can get the curvs better, and go out faster...
get a trail near ur place, and practice, practice and practice... if u have dunes near u, go and do some cross, fast, trying to prevent all the jumps n stuff in the moment, ur reaction must be sharped...
