You know how it goes. One week you're feeling good - hitting the gym or the trail or the treadmill - and the next week you've lost all interest in ever exercising again.

Congratulations: You are normal!

If starting and sticking to an exercise regime were easy, everyone would be doing it. But that's not the case. In fact, fewer than 25 percent of all Americans meet the Physical Activity Guidelines for both aerobic physical and muscle-strengthening activity, as outlined by the U.S. Centers for Disease Control and Prevention.

And it's easy to understand why. Exercising regularly is easier said than done, especially when work, kids and other commitments get in the way. Finding the time (much less the energy) to exercise regularly can be exhausting. But it can also be energizing. Working out makes you look and feel better. So with that in mind, here's a look at how you can start exercising regularly - and then stick with it:

1) Plan for and overcome obstacles You are going to encounter obstacles to your exercise routine. And it's going to happen on a daily basis. You woke up a little late; your son or daughter needs a ride to a birthday party; you ate a cupcake at work. Any and all of these events could get in the way of your workout, unless you plan for them. Once you accept that there are always going to be obstacles, you will be better prepared to overcome them. Always have a Plan B. Woke up a little late and can't get to the gym? Plan to go for a walk over the lunch hour. Had a cupcake at work and feeling down about it? Drink some water and commit to getting some exercise after work. Obstacles happen. But if you plan for them, you're more likely to overcome them.

2) Quiet your inner-critic The voices start the minute things stop going your way. You're not building muscle as quickly as you'd like and you call yourself a failure. The weight is not coming off like you thought it would and now you just want to eat a bunch of doughnuts. Don't get down on yourself. Instead, quiet your inner-critic by reminding yourself of your past successes.

One of the easiest ways to keep the critic quiet is to start an exercise journal the day you start exercising. Write down your daily accomplishments, regardless of how small you think they are. Be absolutely sure to mark down all of the moments when you have worked the hardest and felt the most proud. Then, when you start doubting yourself, open up your exercise journal and take a stroll down Memory Lane. You'll like what you read, and you'll likely be motivated to keep going. And if you still seem to have trouble with your inner critic voice, check out Unbeatable Mind: Forge Resiliency and Mental Toughness to Succeed at an Elite Level by Navy Seal Mark Divine on Amazon.

3) Find a fitness friend Fitness friends are wonderful. They make working out more fun (because you're not doing it alone). They motivate you to show up, work hard and stick to it. And it doesn't have to be an expensive personal trainer, either. It certainly can be a professional, but it can also be your spouse, friend or colleague.

All you need to help keep you motivated and moving in the right direction is someone who is dedicated and supportive. Then, when you don't feel like working out you get to the gym or walking track anyway because you know there is a fitness friend waiting for you (and one who will give you a pep talk when you need it)

4) Start small and realize big success Did you know that you are much more likely to exercise regularly and stick with it if you start small? Why commit to working out every day of the week when you can start by going twice a week and work your way up? If you start with fitness goals that are overwhelming (or even unattainable), you are more likely to become frustrated, discouraged and disenfranchised.

On the other hand, if you accomplish small goals on a regular basis, your confidence will grow and you will begin to see regularly exercise as a part of your life. And you will also be more likely to set bigger goals and continue working toward them.

5) Make it fun One of the most popular reasons people stop working out is the fact that they don’t find exercising is fun.  So find ways to make it fun:  Don't like walking or jogging? Fine, ride a bike instead. Swim.  Play tennis or racquetball.  Take up yoga or martial arts.  Join a fitness center and get involved in one of the many types of aerobic classes or resistance training circuit classes.  Once you get in the habit of some type of regular exercise you will feel better, look better, and actually have more energy!