Grant Peterson has a nice list of easy to do exercises at home in his Eat Bacon, Don't Jog book.
You should be able to scroll through the table of contents here:
https://www.google.com/books/edition...sec=frontcover
I also like to do a short ride to secluded parks and do calisthenics, or the local high school track, which has a about 41 steps up the bleachers.
Already mentioned: push ups; burpees; mountain climbers; crawl like a bug for 50 yards, that's always tough.....