I like to stay outside for most of my workouts but I sometimes opt for a gym session to do some cross training before I head out to the water. I follow Laird Hamilton religiously, his fitness philosophy is in line with mine. When training it's all about activating as many muscles as possible. Isolating weight machines may bulk you up but can leave you weak in areas such as stability.
The rowing machine has become my best friend. It's one of the only cardio machines that requires you to use your whole body. Have you seen professional rowers? They are ripped. I like to do high-intensity intervals of three minutes on and 1:30 minutes off for fifteen minutes. If you're just starting out try one minute intervals. Or I do it like Laird, you can read about his rowing routine in this article http://www.mensjournal.com/health-fitness/exercise/laird-hamiltons-guide-to-mastering-the-rowing-machine-20140818
After warming up on the rowing machine for five minutes I'll jump into dumb/kettlebell exercises on the BOSU (looks like half of a stability ball with a plastic platform.) I'll do all my dumbell exercises besides lunges on the BOSU, that way I'm activating my core, legs, and feet making it a full body work-out. Depending on where you're at in your training start small and work your way up. This is my routine based on my level of fitness. Starting out try just doing 30 seconds of each exercises 3 times. That way you'll be sure to stay within your ability. Be extremely conscious of form and take your time, poor form most often times results in injury.
3 sets of 12 wood chops
3 sets of 12 UpRight Row
3 sets of 12 shoulder press
3 sets of 12 front raises
3 sets of 12 Lateral Raises
To help with leg power I love box jumps. This exercise is great because you can do it almost anywhere. Make sure you find a solid platform like a bench, log, or rock. No chairs (trust me, I know from experience this can go really bad real quick)! With these, I'll just jump until I can't jump anymore.
I always save abs for last. I love this article of Lairds guide to core strength, simple and effective.
It's so important to warm-up before working out or doing any physically demanding activity. Make sure those muscles are ready to give you their best. Give them some relief afterwards by stretching out. After an intensive work-out I always make sure I get plenty of protein to help with muscle inflammation and prevent soreness. I love Skoop's B-Strong protein powder that's plant-based and clean.
Exercise and eat smart! Do what works for you and have patience with yourself and where you're body's at.