Health is wealth in the sense that all the wealth of any sort that one wants to possess can be had only if one is healthy!
Suppose a man wishes to enjoy his life to the maximum. For this he requires abundant supply of resources such as, money, luxuries, company of like-minded friends, etc.
Suppose he has all of these except health. Do you think he will be able to enjoy life? No, not at all! Life's luxuries can only be enjoyed only when one is healthy. A diseased millionaire will not be able to enjoy half as much as healthy labourer who just manages to make both ends meet. As life's delicacies can only be relished in pure health; not in abundant resources. So ensure your health first, before you go on a wild goose chase of any other sort of wealth.
This wealth of health can only be earned and preserved through self-discipline, abstinence, exercise of body and mind, meditation, gratitude, and cheerfulness. So one must give due place to proper nutrition, self-control, physical exercises, proper sleep, laughter and meditation.