exercise while on crutches...

I am on crutches right now for a sore ankle (not sure what i did to it but it is bruised and swollen and I can't put any weight on it). I am trying to find some sort of exercise I can still do to burn calories while I heal- walking with crutches burns some but the crutches hurt my arms :( so I can't go for more than a few minutes at a time. Any ideas?

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