Eat adequate protein and take your calcium supplements. Have someone put aero bars on a bike in a trainer, so you can ride the trainer - hope for bad weather so that all your friends are on trainers indoors too so you don't feel so bad for yourself, lift weights with your uninjured arm - this will maintain overall fitness, even for your injured arm. Avoid anything that require balance and could risk losing balance - like stability ball or hiking. You can still do stuff like squats, stationary recumbent bike at gym, walking. there are waterproof cast covers that you can buy so you could swim (can't recall the brand) my ortho offers water-resistant casts too for an extra charge. get your fingernails painted so well-meaning friends stop telling you that you should. I think those are all my tips. tokie