I have a friend who's willing to take me on a sea kayaking trip. I'm planning to take some lessons from a very reputable local outfit in Portland, OR. I'm looking forward to the classes and to the adventure. I am however worried about my physical strength, and my size. I'm a 5'7" female, weighing about 120, but I have ended up with flare ups of tendonitis after long white water rafting trips. So, I guess my question is, do I have to be in SUPER physical shape, and strong (especially for the roll)?