Just some basics..
It will help the healing process to think in terms having "energy blockages". Don't define , say , the energy blockage in your colon as cancer, pre cancer, whatever... You don't want to manifest that possibility again. Just think of it as energy, neither good or bad. Work on removing energy "blockages". Focus on this as you exercise. Leave those other definitions out of it. Give yourself time in the present with positive thoughts of healing. Try spending the time spent exercising without fears, worries, etc. Focus on the present moment and the exercise. Give yourself this time and space to relax and not think about negative things. This can be challenging, but if you start with making the exercise time free of negative thoughts or emotions, it will spread out to your non exercise time. All you have to do is focus on the exercise, and nothing else. Keep your mind and intention there as long as you can. Your topic heading, " I have cancer and I'm scared." , is not what you want to hold. Just think of things as energy. What energy do those words/thoughts hold. Try to replace negative with positive. Use your time spent exercising to establish positive thoughts, healing thoughts. On another note, regarding diet: (This is suggested by Master Lin) No deepfried foods, spicy foods, or red meat. If you can , eat fresh, in season vegetables. Locally grown produce is good. Apples are good. Try the yin/yang water w/ honey. Get enough sleep. Daily xercise(qigong) is very important, as mentioned by Pete.