There seem to be quite a few of us completing our first run of week 3 today - although all the others I have read found it a little easier than I did! My main problem was that my legs wanted to go faster than my lungs did!
Found it quote tough with breathing towards the end of the 1st 3 min run and took 2 puffs of ventolin during recovery walk as breathing wasn't recovering enough for the next run, but had no such problems with the 2nd 3 min run.
I had taken my inhaler while getting changed to go out as I usually do... and I did try the first bit with my buff over my nose and mouth, but found that my face was too warm!
Hopefully my lungs with get used to this!