Do you ever get to the end of a workout and wonder if you've done enough? You know you could have gone further on the treadmill, or completed another set of exercises. That's when the doubt sets in, and you start to wonder if you're short-changing yourself and your fitness routine.
This is a question which has different answers for each of us, much like "when is enough?"
I would turn the focus of this question back to your goal and your master plan. If you set a goal for yourself, and then created an action plan (process) with daily or weekly milestones which can be easily tracked, then it's really just a matter of doing what you set out to do, and checking in on your progress periodically. (see "the process creates the results".) And since 99% of my readers have goals along the lines of losing weight and getting healthy, I'll focus on a plan for those:
Losing weight in moderation (such as 25 lbs per year), or exercising for health benefits, can require a little patience and some further detective work. Let's look at what's involved in losing 25 lbs per year in more detail:
Losing 25 lbs per year boils down to about 2 lbs per month, or about 1/2 lb per week. That's not very much, which means it can be difficult to tell if you're being successful from week to week, and almost impossible to tell from day to day, at least by standing on a scale.
1.) First of all, your weight probably fluctuates a couple-few pounds from day to day, regardless of what you ate or how long you exercised yesterday. I recommend standing on the same scale, at the same time of day, wearing the same clothes (such as first thing after waking up, after your morning pee, wearing your skivvies or pajamas), 3 days in a row to get a better feel for your baseline weight. Write down the three different weights.
2.) Your diet will play a bigger role in losing weight than your exercise. Exercise will compliment your diet very well - it will accelerate fat loss, add muscle tone and definition, help speed up your metabolism, make you more likely to be more active throughout the rest of the day, and make you feel better about yourself. But exercise alone won't trigger your weight loss - unless you're doing several hours per day, in which case you probably aren't reading my website... Start here, with diet. It doesn't matter whether you're doing 15 minutes or 60 minutes of exercise - if you're diet isn't under control, you aren't losing weight.
3.) Build the master plan. You know your baseline weight, and you know how much you've been eating and exercising before you started making changes. Now you can make some changes to both. Maybe you're plan is to eliminate processed foods, sugar, or carbs, or maybe you want to eat fewer than 1,500 calories per day. (I'm a fan of limiting calories without making drastic changes to what & where you eat, but that's another topic for another day.) Whatever it is, you should know at the end of each day whether you accomplished your eating goal. Do the same thing for your exercise plan - if your plan calls for 20 minutes of exercise 5 days a week, then do it. Now is not the time to question your workouts - maybe you can make some notes to yourself about how you're feeling, but you don't need to spontaneously change your workout plan.
4.) Compare your results against your plan. We know that 1/2 pound per week is hard to measure, so let's wait a little longer before making comparisons. After 6 weeks on your plan, you should have lost about 3 pounds. Get on the scale again (3 mornings in a row) and see how you're doing (compare all 3 weights with all 3 of your baseline weights). If you're making acceptable progress, great - you're workouts are fine. If you're not happy with your progress, now is a good time to edit your plan. If you think you're not working out hard enough, change your workout duration or intensity. If you think your workouts are ok but you're still not losing weight, adjust your diet. Once you set up a new process, stay with it for another 6 weeks before making more changes. Keep in mind that your goal was for a whole year, and you're only about 17% through the year, so there's still plenty of time to modify and correct yourself.
5.) Pounds can be stubborn - check your body too. Many times you'll see your body change, and notice how differently your clothes are fitting, long before your body sheds weight. It's very possible that you've lost inches but haven't lost any weight yet. That's because your body is building muscle from your workouts, so even though you've lost some fat, the scale doesn't know the difference. If this is the case, you know you're moving in the right direction and the weight loss will follow. (and when it does, it's likely to happen faster than you expected!)
So, getting back to the original question, "was my workout long enough?" That depends on your plan. Did you make a plan? Did you follow your plan? If so, then yes - your workout was long enough. If you get to the 6 week mark (or 12 weeks, or 18 weeks), and you find you need to kick it up a notch, then do so - modify your plan to be a bit more aggressive, and then follow your new plan. But trying to wing it on the fly isn't going to work - the process creates the result.
Did you ever have an old teacher or manager tell you to "plan your work, then work your plan?" Turns out they were right.