Take deep breaths, and try to match your breathing with your steps. For example, inhale 3 steps, exhale 3 steps

Yes I think that is too young an age to do 3km runs, wait till she is 5 years old.

1. Normal home made meals are good enough, avoid too much of fast food, chips, sodas, etc.

Yes certainly, variety will keep the kid from getting bored with a single activity

Very important, let him play and run outdoors in the fresh air and in a natural setting.

Best to get the go ahead from the doctor before starting

1. Any exercise and activity will help, let him continue and encourage him without pressuring or expecting anything out of it. Do your best to facilitate the cricket activity that he has taken up out of his own choice.

Avoid before, but afterwards it will surely help.

I think a maximum of 2 such runs per week. Also make him do jumping, sprinting and other agility exercises. Do them in addition to the running, as part of training.

1. I think since running / sprinting is such an integral part of football, just continuing football practice will improve his running. I dont think a separate training for running is needed.

For an endeavour such an Ironman, where hours and hours of training for months and years is needed, the motivation has to come from within. If he shows interest in doing it, that’s a good sign, but if you are trying to force him to do it (not saying you are), then there is a high chance he will lose interest or even mentally and physically burnout

3-5 km is best when racing. During training, do run training as well as agility/jumping/sprinting exercises.

1. Unless doing competitive sports, best to stick to natural sources like eggs, chicken, milk, pulses, cheese etc.