Running in a Studio?

i never jogged or ran a day in my life, probably to medical school. i really didn't pick up until ten years ago, when i trained for my first marathon. Since then, i've been running pretty consistently. There's no numbers, there's no screens. It's really you're a race between you and yourself. And if you feel like you can go all out one day, great. But if not, you say, just go with it.