I'll try and help you with the motivation side, as I had neglected physical activity outside of infrequent recreational sports for many years.
if you can agree with any (or both ) of these motivations for being paleo
- Being healthy.
- Looking good.
Then a really strong rational argument can be made for training.
For me, the biggest motivation (in the beginning, before seeing any results) was that on weight training days I would be in and out of the gym in 30-35mins max x 3 times a week and I should expect results.
On days where I'd do cardio (tabata) I would be in and out in 10 min tops.
The simplicity of doing big lifts and not much else is great. When I first went to a gym more than 10 years ago (was in college then), the dude in charge of the gym gave me this ridiculously long routine. I was working every single muscle at least once a week, and workouts would take 1.30 - 1.45 hours. When I did not have much time to work out, I did not feel like going, or I did a few sets of some arbitrarily chosen ones (cough! bicep curls...cough!) and left. This was hardly motivating.
Now I do a few squats, bench, deadlift and clean and press and know I'm getting much better results than I was with the long routine from back then.
Hope it helps.
