Today, on my 25km/15mi ride in to work, I did about 15min of a HIIT (High Intensity Interval Training) routine, 30sec seated sprint, 90sec light spin. The intent was to do 10 intervals but on the section of 2-lane highway that I was doing it on, I ran out of highway before the complete routine was done (the next section of the commute has too many lights to be able to continue it) so I'm going to shorten the rest period for next time. It was tough but I'm feeling quite fine now (about 3hrs later); I do expect to be quite hungry by lunch in another 90min.