If the challenge is a large one over a longer period of time, are there clear-cut milestones along the way to help you have a sense of accomplishment? If your challenge, for example, is losing 60 pounds in a year, you need to set up smaller weight goals along the way so you can keep up the momentum. Milestones also help you see if you need to tweak the challenge, either lower or higher. If you lose 10 pounds in about 2 months, you are right on schedule, If you have only lost 5 pounds in that same time period, though, you may need to lower the amount you plan on losing in a year. Now if you lose 15 pounds in 2 months, you may want to raise the amount you plan on losing in a year or cut the time down to say 10 months.