Exercising with Knee Pain ?

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I've got really bad knee pain that is aggravated by walking, standing, running, and jumping. Basically any impact. I need ideas for cardio workouts i can do that are super low impact, other than swimming. I typically get all my exercise during bike rides with an extra 50 pounds of toddler and trailer attached to the back. I also take short walks but the pain gets bad pretty quickly and i have to head home. My ortho doc prescribed me narcotics for the pain and boy do they work but i am afraid that by essentailly ignoring the pain by covering it up with drugs in order to jog for example, that I would be making the condition worse. I loooove love love riding the bike but sometimes its too hot or too cold or raining, or i dont have time to go during the daylight. What kind of cardio can i do at home? Ive tried insanity and it was a train wreck. What are Jillian Michaels' videos like? Or the Focus T25?

Thanks in advance everyone!