How long has it been since you exercised - a week? A month? Ah, more like a year? There are many reasons why even the most active women fall out of their established exercise routines. Falling off the exercise wagon happens easily and motivation can be obliterated in as little as one week. 'It only takes one night of coming home from work and thinking, "No, I won't go to the gym tonight, I'll go tomorrow," and then the next thing you know a week has gone by,' says personal trainer, Lisa Brown. 'After a week you forget how much energy exercise will give you, so you get into that vicious cycle of feeling tired and not wanting to exercise.' The next thing you know, it's been two weeks, three weeks, a month...