Gotta say I am really feeling a marked effect from this. On my non-lifting days I'm usually a little antsy and restless. I feel like there's too much energy / tension building up. The heavy bag helps me in a lot of ways:

  • Allows me to channel any energy of frustration / tension / anger in a more productive way instead of projecting onto others (i.e. losing frame) which is just a total waste of everyone's time
  • Seems to have a psychological effect on me as far as confidence goes -- I seem less hesitant to approach people / assert myself / enter into a situations with my views etc.
  • Really gives me a feeling that I could kick the shit out of somebody if I needed to (this may be completely incorrect, but it's beside the point) -- afterwards I feel really jacked mentally and phsyically and I can tell testosterone is seriously flowing. Even if I'd still probably get my ass kicked, it also feels good noticing that over time my punches and kicks are becoming more solid and powerful. There's just something about it. I don't really care about the self-defense aspect as much as the mental and physical foundation and power aspect. I enjoy moving my body in a powerful, impactful way.
  • From a pure fitness perspective I like how taxing it can be. I feel like I am definitely benefiting myself from a cardiovascular standpoint. After 12 x 1 minute rounds of punching and kicking / 1 min rest between rounds I am beat and out of breath. I plan to expand the length of each round over time. Sometimes I'll do a mostly kicks session; these really suck because I feel like my kicks suck ass, but there is steady improvement.
  • I think there is something about confronting and knocking around such a heavy object with a high level of inertia. I can feel the feedback of its mass against my blows, and over time as my blows become more effective, I feel more confident and capable. And it seems to have a carry-over effect through the day.

It is a significant investment, and it does take significant space, but I think it is worth it. And time investment is actually very low relative to the payoff.

Honestly I'm surprised I haven't come across mention of this on the RP boards.