It took me awhile, but I finally understand what he meant by that. You don’t need to spend an hour at the gym to get a solid workout. Take today for example. I was meeting my girlfriend for dinner after my workout, which meant I had 30 minutes to do my shoulders and biceps routine. So I did a circuit workout and boy was it intense. I went from front dumbbell raises to side dumbbell raises to biceps curls and back again. I was relentless and increased the weights whenever I could. I rested no more than 10 seconds in between sets. I was done in 25 minutes and I felt great. My shoulders truly felt (and still feel) sore.
So my point is — you don’t have to spend an hour or more working out to see results. Sometimes if you maintain excellent form, constantly switch sets (muscles), keep your heart rate up, and rest as little as possible — you get a better workout than you do had you spent an hour at the gym.