You didn't specify where the tendonitis was, but I am assuming your wrist. I have had tendonitis is both wrists at different points, common basketball problem. They recommend not using it for 3 weeks to allow it to heal and reevaluate if more time is needed. If you could work out the same muscles with different exercises it would be best. I myself have had it many times, so they recommend me tape my wrists with athletic tape to stabilize the tendon, then exercise and use anti-inflammatories if it flares up. I know this is what professional athletes do as well. You may want to wrap it up anyway after this, but make sure it is stabilized what ever you choose to do.