Have you hit a plateau in your fitness progress? Here are three easy ways to tell when it’s time to ramp up the intensity of your workouts.

1. You’re not reaching your target heart-rate zone.

One of the best ways to gauge your workout intensity is by measuring your heart rate during exercise. Depending on your fitness goals – for example, increasing endurance, improving performance or decreasing body fat – you’ll want your heart rate to reach certain beats-per-minute thresholds to get the best results. If your workout isn’t intense enough, you may not be hitting those zones.

There are many devices and methods that you can use to check your heart rate: built-in handlebar sensors on certain cardio equipment, heart-rate monitoring chest straps, sensor-equipped fitness tracker wrist-bands, or the old-fashioned way with two fingers pressed against your inner wrist and a clock.

Estimate your maximum heart rate (220 minus your age) and take a percentage of that maximum to determine your ideal ranges. As a general rule of thumb, you’ll want to keep most of your workouts in the range of 60 to 90 percent of your maximum heart rate. As you increase the intensity of your workouts, be careful not to push yourself too far – you may wind up overtraining.

2. You don’t feel like you’re pushing yourself.

Ask yourself: Could I be training harder? Answering this question requires a bit of introspection and self-honesty, but it’s likely that you know whether or not you’re hitting your limits. If you’re not sure, try slowly increasing the intensity of your exercise until you reach your maximum exertion level.

A good rule of thumb for high-intensity exercise is that you shouldn’t be able to hold a conversation. If you have no trouble chatting with a pal mid-workout, you may want to bump up the effort.

Experiment with different levels of exertion until you can recognize what high intensity, moderate intensity and low intensity feels like for you.

One way to do this is with interval training. Start with a simple one-to-one work-to-rest ratio to see what it feels like to challenge yourself. That means one minute on, and one minute off. If a minute seems too long, simply reduce your time to 30 seconds. By the end of your first interval, you should have a good sense of what an effective workout will feel like.

If you feel like you need added guidance, consider signing up for personal training. A certified trainer should be able to create an exercise plan that is appropriate for your fitness level.

3. You haven’t increased the intensity in a while.

If one of your fitness goals is continual improvement, you need to be constantly challenging yourself. If it’s been awhile since you’ve altered your workout, it’s possible that you’re maintaining your level of fitness, but not improving it. Your progress may be static, and this can happen with both cardio and strength training.

Try challenging yourself with new exercises. Often times people plateau in engagement and intensity because they need to stimulate adaptation with new movement pathways and neuromuscular connections. For example, if you feel seasoned with a lunge, try performing a front lunge or a lunge with an overhead press to boost your effort level.

With strength training, you generally want to be upping the amount of weight you’re lifting by a small percentage every one-to-two weeks. One telltale sign that you’re ready to increase the weight is if you can bang out 12 or more reps without breaking a sweat. Aim for a weight that allows you to lift 6 to12 reps before fatigue sets in. One of the best ways to know whether you’re improving is to track your workouts. By tracking, you can look for trends over time and definitively see when you last increased the difficulty.

There is, of course, a ceiling for how far you can push yourself, but regardless of how many years you have been training, we all still have room for improvement. However, don’t think of this as a negative – having something to work toward is excellent motivation, and even seasoned athletes are always trying to improve their performance! By increasing the intensity of your workouts and always being aware of how your body handles the added stress, you should be on track for great results.