You're asking and I'm answering.

"Hey Fit! I recently read the new exercise guidelines where it says healthy adults should get 30 minutes of cardio five days a week. Cycling is my release and more time than not I can hop on my bike and go pretty hard for well over an hour and I'll feel so great afterwards. Am I doing more harm than good?
- Cycling Christy

Yes, there are cases where you can involve yourself in too much cardio and do some damage to your body, especially your heart, but it doesn't sound like this is the case for you. Also, if you closely read the guidelines they also state that any exercise above the recommended minimum amounts provides even greater health benefits — though how much is too much has yet to be determined since it varies from person to person. Assuming that you've cleared your activity with your physician, and as long as you're not hurting or feeling badly after your long rides, then I don't see any reason for you to worry. Just be sure to listen to your body and attend to any aches and pains, even if minor. Also, check out these stretches recommended for cyclists, they will help prevent injury too.

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