Updated February 10, 2015.

When it comes to getting and staying in shape, nothing beats the simplicity of being consistent with exercise. Many people start an exercise routine, often in a frenzy of New Year Resolution excitement, exercise hard and long for a few weeks, suddenly realize they can't maintain the intensity of that routine, and just quit altogether. Others will workout so haphazardly that results are mixed and injuries are common.

And one of the biggest workout mistakes people make is working out only on weekends and then pushing to the max every time. That's another sure fire way to get an injury.

Being consistent with exercise may sound like it will take a lot of time, effort, and commitment, but the reality is that consistent exercise can be flexible, fast and loosely scheduled. The key is to find a little bit of time for exercise, or modify your lifestyle to include regular exercise and then train at a level that is appropriate for your fitness. 

Tips for Building a Consistent Exercise Habit

Consistent exercise does not mean you have to have an hour or more every day to train. Consistency may mean you train two hours one a day when you have the time, and you train 20 minutes on a day when you are busy. You can even skip a few days without loosing much fitness, as long as you get back to exercise quickly. 

If you want to be consistent, it's helpful to cross train. Doing the same routine day after day is boring and will often lead to burnout, overtraining or an overuse injury.

By mixing up your routine you can be more regular with activity and be less likely to get bored or injured. Think about adding low-level activity into your routine a few days a week: walk to work, walk for errands, bike to a friend's house, walk while you socialize or during a phone call. Adding walking into your routine keeps your exercise consistent and allows you to limit the sweaty gym workouts to only a few days a week.

Don't make the mistake of letting one missed workout turn into two and then three. This is a slippery slop to becoming an exercise drop-out. You can lose your fitness and your exercise habit pretty quickly if you let too many days pile up between exercise session. So if you have missed three days of exercise, force yourself to do something—anything—for about 20 minutes. Try a quick home workout, a bodyweight routine, go for a job, jump rope, or play a game of tennis just to get moving.

Don't overdo the high intensity training thinking you can make up for missed workouts. HIIT is intense, and if you aren't a regular exerciser, it can be too much too soon. Inconsistent athletes who attempt intense exercise often end up injured. High intensity training may be the latest exercise fad, and it is a great way to build fitness fast, but it's only useful for those who have a good foundation of strength and cardiovascular fitness, as well as good body mechanics that come from starting slow and progressively becoming more and more fit. If you want to try HIIT training, you really need to master consistent exercise first.

How Much and How Often To Train

How much exercise is enough? And how often should you train? The answer depends on what you are trying to accomplish. If you simply want to maintain a good base of fitness all the time, train a little bit, all the time. In this scenario (most regular people trying to be 'fit,'  a consistent exercise program includes some activity every day. It does not mean training hard every day. It may include walking 30 minutes one day and doing a full body strength routine another, taking a yoga class or swimming the next. The time, type and intensity of the routine will vary from person to person and will change according to your fitness level. Even an elite athlete, who trains regularly throughout the year will sprinkle in a few recovery days of little to no exercise. So mix it up, do something ever day or two and always pay attention to your body and any warning signs to back off or go harder. 

If you are training for a specific event, race or sport, you need to be able to put it the time required to safely compete in that activity. If you want to run a marathon, but only have five hours a week to train, it's just not a good idea to run a marathon. You will most likely get injured or fail to make it to the finish line. Be realistic about what you really have time for, and plan your goals according.

For general health, your training guideline can include healthy eating and moving easy and regularly in the first months to build a habit and then push  up the duration and intensity of your workouts.