I used to do a lot of treadmill running (as I had a gym membership & went to the gym several times a week with friends) and so I won't say a word agin it. In fact I could have done with one this winter just gone!
Where could it take you?
Well, ten-odd years ago, a friend was propelling me & other friends round a 3k loop of the "hills" (gentle rises!) in town, and we were powered mainly by the force of Complain And Grumble. I was doing exercise to keep my stress down and my health up. We wore cotton tracksuits and pink sweaty faces.
Since then, my distances went up, I joined not one but two running clubs and through them and through running forums here and elsewhere I have made a lot of new friends. I've trained and raced (not very fast, always, but I mean to say there was a number pinned to the front of my vest

) all over the world. I have a drawer full of hi-tech running clothes and gadgets, a cupboard full of running shoes, and a multi-hook-over-the-door thingy full of race medals.
And there's a lot of stuff (club cross-country races and road relays, hash house harriers, local Vets League athletics competitions, local road race series, tower races, corporate team races...) I still have waiting on my to-do list.
Where could it take you ....? Anywhere but the Tour de France, I reckon! It's up to you.
There's no rush though... the oldest guy in my club still running regularly with us is 79... so you've plenty of time to have a go at things and find out what you enjoy