Why don't you commit to aiming for a full 18 minutes. Once you get there, if you feel (ha ha!) you can do another minute or two, go for it. When I was running regularly, no matter how fit I was, I usually thought I could only run two miles tops. And I was always beat at the end of the run. But I could have done twice that and felt the same way at the end of my run.
I think it's a "mind thing". We think we can only go a certain distance, but we've got more in us than we know.
Plus, we're women.
Great stamina and pain endurance.


I'm going for a full week of movement

I know you can run the full 19 minutes! It is nothing! Only 60 more seconds than 18! In order to motivate you I just ran my full 20 minutes with no walking! (Shhh, don't tell my coaches.)