That's it. Help him make this a habit.
A habit is formed by a culmination of these three things:
Why to do
What to do
How to do
He needs to understand WHY he should exercise and eat right. The more he reads about the benefits of eating and exercising regularly the more knowledge he'll have and knowledge is powerful.
Then he needs to read up on HOW to eat right and exercise. Too often well meaning folks know why they need to do something but have no idea on what to do. Again, the more he reads the more he'll know what to do.
Lastly, the implementation of of HOW to do an exercise or make a healthy food choice. Does he know how many calories he should eat? Here's a start: www.freedieting.com/tools/nutrient_calcula
Does he know how to make a basic weightlifting routine? exercise.about.com/cs/exerciseworkouts/a/w
All three of these things help form a habit and once a habit is established then no extrinsic motivation is needed, it's all intrinsic.