I get the same feeling on stationary machines for cardio. When I'm playing a sport, such as hockey or tennis, it's all "go chase after that small yellow (or black/whatever) object as fast as you can", while on the machine it's mainly "suck it up for (x) minutes". I can't push myself nearly as hard on machines because I hate it. That's another reason I've been doing various agility exercises (ladder work, lateral jumps, plyometrics, etc), because those are actually fun (relatively speaking), and I have much less trouble pushing myself much harder.
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