What's a fun, cheap, solo workout someone can do at home?

Bonus points for low impact and cheap/free. I have a foot injury and can't run/bike/hike for a bit.

Editing this to say:

• Thank you all for the suggestions, I love the Lemmy community, and,
• I know a lot of workouts can be done at home, and these are all great ideas. However, I bike/hike because I have trouble motivating myself to just work out as an activity. I trick myself using fun, but I don't know how to make indoor excercise exciting.