In order to make the most of a change in diet, some physical effort should be utilized. You don't have to become a body builder, go through grueling cross-fit training regimes, or run 5 miles a day. Research into the field will prove that high intensity exercise in short bursts that fatigue the muscles is quite effective in engaging the central nervous system and muscle groups enough to compliment a healthy eating lifestyle.
From my personal experience, I began a very high intensity program, P90X, when I first started Gluten-Free and then engaged in a number of HIIT routines after getting into Paleo full swing. I am a very low-key person for the most part but adding a routine to my daily life really pushed my energy levels through the roof. I was doing the usual of slamming protein drinks and consuming multi-vitamins until I realized that I didn't really have to do all of that. I will say that P90X is a very robust program and anyone sticking with it will definitely show major improvements in strength and agility. It helped me to go from what's called skinny-fat to a ripped skinny individual. Tony Horton can be a drag to listen to over and over and over again (or at least his jokes) but the program itself is worthwhile and even doing the base minimum effort while eating properly will go a long way.
After P90X I researched further into different training programs and found High Intensity Interval Training. P90X consumed a LOT of my time and I fell off the wagon not wanting to engage in at least an hour and a half training program at the end of a long day of work. It took a lot of motivation some days. HIIT would be my ticket. I could engage in fierce blasts of working out and be done in less than 30 minutes depending on how much time I spent with stretching pre and post.
I am now reading a book, Body by Science, which is tying a lot of things together for me. It's giving me the details I lacked on how the central nervous system and muscles work in conjunction along with details on metabolic cycles. From my own research and through this book I am working on putting together my own routines for home use. The idea behind HIIT is to exhaust the muscles, pause, and then exhaust them again before the fast-twitch muscle fibers have a chance to recover. In doing so you're dumping the glycogen stores in the muscle fibers to a state of fatigue that cannot be achieved in the typical aerobic workout. Utilizing this methodology has shown the best in performance boosting without a plateau.
Many people that spend their days jogging around the neighborhood think they're getting a good workout when in actuality they're only getting good at running. If you put that same person on a stationary bike next to someone else just beginning it is likely they'll perform the same if not worse than the other person. The reasoning is that they've conditioned their muscles just for running and not for biking. Your body adapts and you'll definitely show improvement in running, adding extra miles to your routine as you get stronger but you're only getting good at that one thing and likely damaging the rest of your system by putting it out of balance. Habitual running has been shown to actually damage the body in more ways than one. There is a reason why supposedly perfect health runners collapse from heart attack. They're not engaging the full body system, the muscles are actually stagnating in a pattern, and they're really not much healthier than the next person.
I'll continue further into this once I am comfortable in tying the loose ends together but I feel at this point from my own experience so far that high intensity exercise is definitely the way to go. So, someone that is first getting starting with Paleo and wants to compliment it with training I would definitely recommend just quick and intense exercise programs and then substantial recovery to allow growth and repair. Work harder in less time. You'll find the most benefit and you won't be wasting your time on extended workouts.
Some people will disagree with this aspect but if you're a high performance athlete then this may not necessarily apply. Of course everyone is different and may need different tools to get the job done. Some people naturally enjoy working out but I myself enjoy efficiency and would rather spend time elsewhere where I can gain optimal performance in the least amount of time.