is a great way to approach training, but you'll have to incorporate some planning if you are aiming for a half-marathon. As long as you get the long runs in, and mix it up with some shorter/faster/hillier stuff you will be fine. Listening to your legs

. For my first marathon I had planned what I would eat and when, then trained to that. On the day, I was past halfway before I remembered my plan. Surprise surprise, by mile 20 I was shot... – amadeusI took a drink at every single water station because I

training plan and you will get faster and fitter. If you are training for a race (highly recommended, especially somewhere different to where you live and train), then you need to run outside. If you run because you love running then this is a moot point