When I'm home, I do fine. The other day, after not having run for a week, I went and cracked off a nice 17 miler. This was surprisingly easy to do, and the "easiness" gives me hope that I will be able to complete my ultra in two weeks without too much difficulty. (Hah! It might actually take me two weeks!). Oh, I know that 17 does not equal 31, but let me delude myself a little while longer.
I ran the Emigrant Trail, site of many long runs for me. I usually leave my car at one end and get dropped off at the other (I'd show a map, but I'm writing this on my phone and that's just way too complicated). Depending on exactly where you park, you're either in for 8.5 or an 11 mile run. This time, I parked -- and doubled it, for my 17 miler. A lovely Tahoe day.