“You did your cardio after your strength training, right?” says Jimmy Amutavi, my L.A. Fitness trainer.

“Ummm…. was I supposed to?”

I was proud of myself for going to the gym. But even after reading countless articles to find every trick to make exercising easier, I had never heard of this rule.

And so I grilled my trainer, Kenya native Amutavi, for other exercise guidelines that I might not know. As it turns out, there are many common mistakes people make at the gym that stunt their exercising efforts. Amutavi offered these tips to improve the average workout.

1. Do strength training before cardio workout.

When you do cardio before strength training, you’re using up energy you would have used for resistance training. According to Amutavi, by the time you’re done with cardio, your body won’t have the right kind of energy left for resistance training. Instead, your body is left with fat as the last source of energy, which is not enough to sustain weight lifting.

If you lift weights first (using the body’s first form of energy), you’ll use reserve fat (the fat visible on your body) for cardio. The cardio will burn the fat.

2. If you’re only doing cardio, do it first thing in the morning.

In the morning, before you do anything else, your body hasn’t stored any carbohydrates to use for energy. This leaves reserve fat as your body’s only remaining energy source. Do cardio when you wake up and you’ll burn that fat before breakfast according to Amutavi.

3. Know proper techniques.

Amutavi said each exercise has strict rules and structured form that maximize benefit and minimize injury, and it’s not necessarily true that the more weight you lift, the more muscles you’ll develop. In fact, you may be using the wrong muscles for the wrong job. Before you hurt yourself, make sure you understand the rules of your workout. You’ll reach your goals faster without damaging your body in the long-term.

4. To build muscle, do high reps with a challenging weight.

To build big, impressive muscles, do everything. Amutavi advises focusing on achieving high numbers of repetitions at a weight that’s going to push you. As you build your endurance, you can work with heavier weights and slowly build muscle mass. Focus on increasing your endurance because you’ll be able to workout longer and gain the muscles you want.

5. Don’t work out the same muscles two days in a row.

After strength training, give your muscles at least 48 hours to recover before exercising those muscles again. All the cells that were broken down during the exercise need to be repaired in order to get back to the shape you were in before you started exercising. Recovery is just as important as the workout itself. If you’re still sore after 48 hours, Amutavi says that it’s crucial to wait until you’re fully recovered.

6. Different forms of cardio achieve different goals.

Know why you’re doing cardio. If cardio is your warm-up before strength training, do at least eight to ten minutes to warm your muscles and get the blood circulating. This will prepare your body for resistance training.

However, Amutavi said if you’re doing cardio simply to keep fit, then you’ll want to challenge your heart. Don’t go at a steady pace. Play around with the incline and speed on your treadmill. This way, your heart will be put through its paces. The ultimate goal is to lower your resting heart rate, because it signifies a stronger heart that can achieve adequate blood flow with less effort. A healthy heart is a slow heart.

7. Diet (and the right attitude) makes your workout more effective.

If you’re serious about your workout, you’ll be serious about your diet as well. “You’re required to know a little bit about nutrition,” Amutavi says. In other words, try not to justify a donut with a mile on the treadmill too often.

On the same note, Amutavi also stresses dedication to keeping fit in all aspects of your life. At the same time, don’t expect drastic change overnight. Just as it takes time to put on weight, it takes time and the right attitude to shave it all off. Be patient, and don’t focus on unrealistic time goals.

8. The workout doesn’t end when you meet your goal .

Even when you’ve achieved your weight-loss or muscle-building goals, you’re not done working out. Amutavi warned that it’s easy to revert to old habits once you’ve achieved your target weight. This is where the actual work begins—maintenance. And through it all, you must stay disciplined, focused and committed to exercise as a lifestyle.