Whether it’s trying to trim down and get in shape for an upcoming beach vacation or to look good for a big high school reunion quickly approaching, you want to see fitness results fast.

The fitness industry is flooded with promises to lose weight and get in shape in mere days or weeks, but are fast results really possible? If so, is that good for both your physical and mental health?

As consumers, we’re trained to think that fast results are possible because we’re promised it on infomercials, in ads for fitness studios, and in magazines. So when we don’t reach these goals quickly, we not only waste time by following a program that didn’t work, but we also get frustrated and burnt out, causing us to potentially end up in worse shape than where we started.

In a perfect world, getting in shape would be instantaneous. However, that’s not how the human body works. By setting realistic expectations and working with a trained professional who can create a custom program designed to help you reach your goals, you can confidently work through a fitness program that will give you long-lasting results. Here’s what you should expect:

Month 1. After the first month of an effective fitness program, it’s important not to focus too much on how much weight you’re losing, or how many pounds you’re lifting. You should start to feel more energy during the day, mostly due to the fact that your sleep is much improved, especially on the days you work out. You should also feel a significant improvement in range of motion due to the fact you may be using muscles and joints not used previously.

Month 2. Two months in, you’ll start to realize that you’re less out of breath performing the same activities due to improved cardiovascular performance. The muscles in your arms and legs will start to feel tighter and stronger which is due to the increase in muscle mass and decrease in fat you are starting to experience.

Month 3. After three months, you’ll start to see more of a significant improvement in strength and endurance along with a noticeable improvement in resting heart rate, blood sugar levels, blood pressure, and other health indicators. For some, results are harder to see but be patient as changes are accumulating and may appear seemingly overnight in the coming weeks. It’s not uncommon for those on a program to feel little to no result in certain aspects of fitness at this stage, but it’s important to realize that fitness results are not perfectly linear. For example, while a safe weight loss program may suggest you’ll lose one to two pounds per week, you may only lose one or two pounds in one month but then lose eight to 10 pounds the next month. This is why it’s important not to give up on a program if you have small setbacks. Big results may be right around the corner.

Month 4. At this stage, clothes will start feeling differently. This is usually when you’ll start hearing friends and family commenting on how different you look, which will only motivate you to continue training.

Month 5 and beyond. This is a critical stage of the fitness program because individual results start to snowball into bigger, cumulative results. For example, because you’ve built up muscle mass, your metabolism has now increased and made weight loss easier, which in turn, means you have less weight to carry around, putting less stress on your heart and lungs, causing you to be less out of breath. This is just one example of how one aspect of fitness (muscle mass) can affect several other aspects of fitness and health.

As you pass the 6-month mark, it’s important to continue working hard even if you find your results start to slow. This is natural. As you get closer to your goal, you may need to get more strict with your exercise and nutrition routine. If you have reached your goal, you may also want to continue to maintain your results you worked so hard for.

Knowing the realistic expectations of your fitness journey is the first step towards being properly prepared to succeed. By having your expectations set on a realistic program that will give you results, you’ll be less likely to become frustrated and give up on a program that may have promised you the world.

Brian Maher is the owner of Philly Personal Training, a Philadelphia-based studio offering personal training, physical therapy, and nutrition counseling.