My Running Detoured by Foot Pain

Although I would like to train up to be able to run in the upcoming half-marathon races (even possibly marathons) this fall, I have developed a nagging pain in my right foot that may just derail any substantial running for a while.  I am looking for ways to get around this problem, which involves pain that only occurs at impact, neither existing at rest nor with simple muscular exertion.  So right now I'm working at alternative forms of exercise, including getting my old dilapidated cheap-o bicycle out of the shed and riding it around the neighborhood.  I also have a portable stepper exercise contraption that I can use as a "no-impact" exercise...not to mention that I can do modified push-ups using it that serve as an alternative to abdominal crunch exercises.  And then there is also the elliptical cross-trainer machine at my local 24/7 gym.  In any event, I have to give my foot enough time to heal while avoiding aggravating whatever problem currently exists.  I haven't given up on my race plans...well, at least not in a general sense: the upcoming October events may not be feasible for me, but toward the end of the year I see no reason not to resume competition...which for me, isn't against any other runners, but rather to simply finish with reasonable times...