Sometimes I think we all get a bit carried away with this running "thing" - as though the act of running exists as a separate entity to everything else in the World - so we are either running or we are not. But what we are really doing is doing a form of cardio exercise. Some people choose to do their cardio exercise on different kinds of machines in a gym - but the form we choose is the act of putting one leg after the other out on the road. Now what is important during this form of exercise is that our heart rates are elevated - it doesn't really much matter the manner in which we get our hearts rates elevated - so long as we do so for 150 minutes per week??? (according to the American Heart Foundation)
So the next time - you get a sore ankle , run out of breath, have to wait for a traffic light - worry not because your heart will stay at an elevated rate for at least a minute or so ( I am so fit now that it is only about 30 seconds for me now ) - and the purpose of your cardio workout has not been in any way "ruined"!!