Okay, what you need to do is start sprinting. Keep the distances under 100M. Also, do some bounding and repetitive jump training. Along with one legged squats, this should do it for the lower body. You can also do some GHRs or one leg hyperextensions, both weighted of course.
For the upper body, don't worry about it too much. If you keep a strong arm drive in sprinting it should help your development some, or at least maintain what you have.
For conditioning, run 400M as quickly as possible keeping 90 seconds between sets. Do this until you're about to puke. Build up your tolerance over time and try to do another lap whenever possible.
This may not seem like much, but you can become one hell of an athlete and build an attractive physique without ever touching weights. Just remember, in the sprints(non-conditioning), stress quality over quantity and allow yourself to recover fully.