Can anyone help please. I am a really keen runner and have competed in a number of marathons PB 3:11. Six year’s ago I was diagnosed with stage 3 Bowel cancer. Following initial Bowel surgery and a bunch of radio and chemo (9 months worth), it then spread to my liver and on 5 separate occasions to my lungs. Anyway, throughout all the treatment I carried on running which really helped me. More recently I have really struggled as the last treatment left me with only my right lung. I am hoping to do London marathon again next year but can’t seem to get any speed or distance back. Wondered if there were any runners out there with one lung who could offer some advice please. Thank you.