Sarahtink - Don't be too afraid of the kayak tours. I think Kickapoo had an extra special trip and paddling two through the water in a tandem is a heck of a lot harder.
Have you ever paddled a kayak before? If you know motion to paddle a kayak you should be fine as long as it's not too windy.
We do own a kayak but really only use it for a week in the summer for little paddles. I must admit I was a little apprehensive when going on the the tour. I am now over 40 and in the worst shape in my life both weight and strength wise. What shape you used to be in and things you used to do doesn't matter does it?? I was even concerned that the guide would have brought a life jacket big enough and I wouldn't fit in the boat, etc.

Everything was fine. [a break to regain composure after bearing soul] Really, I think it is doable to most, at least most that have paddled once or twice before, especially if there is little wind.
Go on one of the non Disney sponsored tours. I think you will find them smaller and able to adapt to your needs in a smaller group.