I felt really nervous today at the thought of running for 20 mins, worse than I've felt for any other run as it seems such a big step up in time. Anyway, I thought I'd just go for it and see how it went and once I got past the first few minutes and settled down, it was OK. Well the last 2 minutes weren't easy but I got through it to the end.
Now I feel a great sense of achievement, from nothing to 20 minutes in 5 weeks is almost unbelievable.
If you're facing this run and fear it being a big challenge, you can do it. The challenge is 90% mental because as Laura says you've done all the hard work getting to this stage. Hope that helps