Ellipticals are fun! But I prefer running outside. Much more fun, fresh air, and it's free. And if I joined a gym, I probably would have an excuse why I couldn't go. With running outdoors, there really is no good excuse for me not to.
The longest forwards I have run is a half Mara I did last month (21k). And which I quietly threw up after since I drank way too little water.
I am currently training for a 10k and a fun run called Tjurruset since its coming to my area and I always wanted to do it :
https://youtu.be/-HSKcWDpx1w
Just fun training for different runs. Makes you feel like a pro