Over the years I have found several things that help the kayaker, that have nothing to do with kayaking. I thought I would pass a few of them on.
Martial Arts/Tai Chi: When I say Tai Chi and Martial arts what I am really saying is internal and external arts. I learned early on that people who practiced martial arts - particularly people that used weapons like the staff - took to the movements of kayaking very easily. You will find it easier to accept the concept of rotation faster if you already understand this movement from working with a staff, or throwing a punch correctly. Tai Chi teaches 'flow' and balance and patience better than anything I have ever seen. You also learn that power can come from slow, balanced, flowing movement, like a forward stroke.
Meditation: If you have been reading this blog for any length of time you know that I consider paddling a meditation. So meditation on dry land can only be good as well, right? I recently read a description of meditation that I liked, it described it as lifting weights for the brain. We spend our days focusing on many pieces of information all at once. the phone is ringing, while cooking dinner with the TV on, and the dog wants to go out, and little Johnny needs help with his algebra. As a species we do much better when we are focused on one thing. Our minds have become the kings of short attention span theater and this is never better illustrated by the friend you have that only calls you when they are driving somewhere and doesn't have something to do in the car. They will tell you it is a good use of time, but the real reason is that they aren't comfortable with their own thoughts. And they aren't comfortable with their own thoughts because they are constantly drowned out by a ridiculous amount of stimulus. By meditating you will learn to focus your thoughts down to one thing, your breathing. (When I am paddling I focus on the movements of a paddle stroke.) By doing this repeatedly you will make it easier to do - I think it is one of the more difficult things I do - and will give you a level of calm and peace you have never experienced before. You will also see the world with a clarity you have never seen before.
Neti Pots: If you are unfamiliar with a Neti Pot, it looks like a small tea pot. You put body temperature water in it, and a salt solution - so the water is the same salinity as your body - You then put the spout of the tea pot to a nostril, lower your head a bit, and pour. The water will go in one nostril, through your sinuses and out the other nostril taking all manner of things with it. What does this have to do with Kayaking? It is wonderful after a day of working on rolling when all sorts of liquid ends up inside your head. You can flush it out, and it will leave you feeling cleaned and refreshed. It is also a way to get the last of a cold out of your nose, And just recently I used one as I felt a cold coming on and the symptoms went away. Though this could have been a psychosomatic reaction.
Yoga: Yoga will help balance, and patience, and clarity and stretch. You want to learn to Greenland roll, your going to need to be flexibly and Yoga is the key. I was born pretty flexible - to the point that yoga instructors have commented on it, it certainly isn't through hard work on my part! - but you can gain a remarkable amount of flexibility and strength through yoga classes.
There are others, for more 'hard' skills, like land navigation sets you up for the more difficult water navigation, but this is another post.