Warning: Link building is addictive. It's like working out. Once you get going and you see results, you want to keep on. You want to do more and more but what happens if you slow down or stop your efforts? With exercise, you'll gain weight again, most likely. With links, it's not as straightforward. Will stopping, or slowing down, raise a red flag? Will your past results look like they came about through spammy efforts?