The advice given is excellent. Technique and posture are important. When taking up a new dynamic sport like WS or snow sports the novice tends to tense up with muscles in lock down rather than working in a complementary way. That said, I note that many WS people do 'weights' and endurance things like commuting to work by bike or running - this way you can stay on the water longer (especially when the wind is really in) and it helps to ward of injuries. Basically do the kind of exercise that your body tells you it wants. Important thing is to do it and frequently but without becoming a exercise junkie.
And welcome to the world of WS.