In addition to what everyone is saying, you might be exercising too hard. The fitness industry, paradoxically, pushes the idea that exercise should be hard, per

In addition to what everyone is saying, you might be exercising too hard. The fitness industry, paradoxically, pushes the idea that exercise should be hard, perhaps because it’s an easy thing for people to believe. Hard work feels like it’s getting you in shape. But most cardio should be easy, like 60-70% your training maximum heart rate. Many elite distance runners follow an “80/20” rule, where 80% of their training is easy in this way. But 100% is fine also. If you’re not used to it, this feels odd, like you’re going too slow and doing nothing. But measure your time and distance and the improvements will be obvious. It’s like training for free. The only ingredient is time. After a good long low-intensity run I feel less fatigued than I did when I started. Meanwhile hordes of people suffer through these awful spinning classes. It’s like they think exercise should make you feel worse instead of better! People who feel the need to put in effort and who aren’t distance athletes are likely much better served by adding HIIT and/or strength training than by pushing steady-state cardio too hard.