It's absolutely the most intense thing I've ever done. You wouldn't know from looking at me (since I'm carrying an extra 50-60 pounds right now), but I've always been a bit of a gym rat (I just really, really like food- especially sweets and carbs). I'm not happy unless I feel like my legs are going to cave from underneath me when I leave the gym. But I started doing Tang Soo Do about a year and a half ago and it takes my workouts to a completely different level. After doing a week long camp in July, I realized that even carrying the extra weight my athletic ability now far exceeds my old skinny self.
Today will be a more difficult day for motivation, only because I went home after work and need to physically leave my apartment again (M,W,F I can just go straight from work because there's a 5pm class on those days). I know I'll feel great once I get there; it's just the getting back out the door.