If you're hard on your shoes because you're heavy or you just happen to have a pounding gait, look for models with more durable cushioning. The polyurethane of the Nike Air Healthwalker III is a more durable foam than the EVA found in most athletic shoes. Sometimes manufacturers boost cushioning life with materials like gel, air, and special foams. By viewing my shoes from behind, I see that I underpronate. First a clarification.
Pronation is a natural cushioning mechanism.
It's the inward roll of your foot that happens on every step, and a certain amount is perfectly normal. Too much inward roll is known as overpronation and can lead to knee or hip injuries. Underpronation is much less common, though it, too, can lead to problems. An underpronator's foot rolls in too little. The solution is to look for shoes with generous, durable cushioning and a design appropriate for normal feet or underpronators.