I began the hike/run from Arrochar train station. I wore trail running shoes as I planned on running as much of the hike as I could-which turned out to be around half of it. I followed the path towards the cobbler, and then turned right when I got past the trees and could see the river. I decided on Beinn Narain first as it seemed to be the most challenging of the three. There were little flags in the ground the guide hikers up Beinn Narnain, but I ended up getting lost a few times, and had to awkwardly climb up grassy slopes with my hands. I finally got to the rocky part of the mountain (there was a false summit if I remember correclty), and after a bit of a steep (but fun!) scramble I made it to the top-this was definitely the most difficult of the three mountains. I descended down from Beinn Narnain, and Beinn Ime was clearly in sight a bit beyond it. Although higher than the other Munro, the ascent was quite a bit more flat, but a bit boggy. I was able to run up and down most of this ascent/descent. I did actually fall backwards in the boggy section on the way down-so in a way it was more treacherous than the previous munro... I had done the Cobble twice before, so decided to throw it in swell because the view is amazing. The ascent up the Cobbler is quite steep, but it's not a scramble. Once I got back down to the river I was able to run all the way down the to the lake. I ended the hike/run in the pub beside Loch Long, where I felt very light and my body felt quite numb (in a good way!). All in all, I hiked/ran 24km in 5 hours and 30 minutes- I initially thought I wouldn't do it in less than 6! The hike would definitely take a few hours longer to do if you don't run the downhill bits, and you are stopping along the way for lunch. Definitely adds to the fun for me to do it all in one push with breaks of max 3-5 minutes, definitely recommend this hike! (It also magically helped loosen out a running injury behind my left knee).