Hard and exhausting (but it's a good exhaustion), yes, boring and painful, no. If it's boring you're spending far too much time at it and with not nearly enough intensity. Maximum intensity requires maximum focus, you can't go on autopilot like you can doing "cardio". At any rate, the HIT program I'm doing takes one 12 minute session a week, hardly enough time to get bored. As far as pain goes, if it's painful you're doing the wrong exercise or doing it wrong.