Have a heart rate that instantly goes very high when beginning to exercise. Have workouts showing high calorie burns. Be excited about it. Continue to exercise on a regular basis. Begin to feel comfortable with the current workout. Then, constantly begin to burn less and less calories for the same workout. Like… 1/4 less.
Even though I know it is a GOOD thing that my heart isn’t instantly hitting the roof – it means I have to begin exercising more (either length of time or difficulty of workout) to still burn my weekly target.
Now THAT can feel frustrating.