This is a spoiler but if you'd like another option begin highlighting here:

You can make a special stew to make the villagers exercise. This will help them earn building skill. The stew has all red herbs in it. This works on children also. The adults can swim, lift boulders or jog around the island. Jogging can only be done if you haven't built your sewing hut. Kids can lift boulders or jog, but again only without the hut. Nursing moms can jog too....without the hut. It takes awhile but some players have Master Builders at age 14! If the villager begins an exercise that isn't helpful, ie: jogging after you have completed the sewing hut or kids swimming, just pick them up and repeat until they head toward a productive exercise.

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Hope this helps!