Focus on the basic human movements and don't bother with weights.
Build a daily routine which includes press-ups, burpees, squats, planks, leg raises, situps. Aim at increasing the volume by adding 5 reps a week and keep your heart rate up during the session by including jumping jacks and climbers at the start and halfway through. Remember the acronym KISS (Keep It Simple, Stupid).
Example;
Morning:
5 min Plank (Press-up plank > elbow plank > side planks > elbow plank > press up plank)
3x20 Hand-release press-ups [Increase reps by 5 each week]
3x20 Deep squats [Increase reps by 5 each week]
Evening:
3 Sets of:
75 Jumping Jacks
25 Burpees
50 Leg Raises
75 Climbers
50 Sit-ups
25 Burpees
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Run 3 times a week with a rest day in between.
Run 1: 2.4km and keep adding 500m each week. The aim is to run the first 2.4km of the session in your "fast-time" and then back to endurance speed for the rest. Get that 2.4km time below 10 minutes.
Run 2: Run 2.4km to a decent straight section of road. 4x100m Sprints. 3x200m Sprints. 2x400m Sprints. Jog home.
Run 3: Endurance run. Start at what ever your longest distance run is and keep adding 1km each week. Sprint up any hills and sprint the last 400m to expel any left over energy. Your brain gives up before your body does so just keep going.
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Cannot stress enough the importance of dynamic/static stretches before/after exercising.
Take Sunday off.