Ok, I was intentionally trying to get your attention by saying "force". What I really would like is some way to encourage activities other than leveling, sometimes. However, it seems impossible when they become obsessed with leveling.
Also, I have started a few alts and I can tell you it is just as fun to play at low level, maybe even more fun. True you get new nanos and equipment when you level, but you also get harder mobs, so nothing really changes at all.