An exercise program is viewed by many as akin to climbing a mountain; once you’ve reached the summit or goal, you walk back down to tell everyone about your accomplishment and celebrate.
In reality, exercise is more like walking up a downward escalator; if you stop moving, you start losing ground and moving backward.
For example, athletes can start to lose their muscle strength in about three weeks if they’re not working out, according to a 2013 study. Athletes typically lose less overall muscle strength during a break than non-athletes. Newbies and less frequent gym-goers will see declines more quickly and evidently.
Strength and power will decrease before muscle size actually decreases, which occurs after 4-6 weeks of inactivity. This means your physique isn’t the first or best sign of the decline that results from an exercise layoff. Strength losses are deceptive.
Your aerobic capacity (endurance) will also begin to decline after about a two-week layoff. In fact, detraining typically occurs faster with aerobic capacity than it does for muscular strength. A couple of days off can be good for recovery, especially if you’ve been working out really hard. It’s the longer breaks that should be avoided.
So, if you’ve spent months working hard at the gym and getting yourself into shape, you can lose all your hard-earned gains after just a one-month layoff.
I always tell people that it’s easier to stay in shape than it is to get in shape.
The key is not to give up. You’ve worked too hard and spent too much time to let it all slip away.
The reality is that there is no fitness savings account to bank on after you stop working out. Your fitness level accrues only as long as you maintain it. Once you stop, your ‘balance’ starts to fall. Fitness is an active and ongoing process. 
The simple message is: Don’t quit! Exercise is really good for you, physically and mentally. Letting all those hard-earned gains just slip away is a bad idea and, ultimately, a recipe for disappointment and regret.
Stay the course. Stay in Motion!