First of I'm 6"2 and 10 stone with an extremly fast metabolism. My plan is to join formation recee and want to specilise in the para/commando role. I'm a bit underweight and not at a great fitness level and need to sort it out I have 3-4 months to be prepared, my routine is currently lifting weights 3x a week doing 2 muscle groups a session with 3 excercises for each (I've no money for the gym and just have a bench with a barbell with weights and a chin bar. I'm going for 3x a week running but worried to much will cause weight loss I will struggle to gain back will 20 mins fartlek be enough say twice a week then a long distance 1x? Haven't yet timed my mile and a half which I know is most important bit so know what to improve by but unless I specilise at a later date need prepare for the 10 miler also and be able do the 9 min 30 mile and half.