Exercise is nature's mood enhancer, to be sure. Just requires the ability to tolerate sustained pain for the delayed gratification of reduced anxiety and stress as well as mood lift and guilt-reprieve.
I definitely overdo it. Last night my eyeballs felt dry (not sure if it's related). On the weekends I don't stop. I don't accomplish much, either.
But I decided to lay off during the week because the kava I had prevented me from getting to sleep, and I felt no withdrawal symptoms or cravings.
People on these forums have described some sort of allergic reaction to Kava in some cases, and it is relieved (obviously) by refraining from taking more, and much of the time it just needs a few weeks off, while in rare cases people just can't do it at all even after a break.
Last summer I was drinking a lot of kava. I also do a lot of road cycling in the summer months, so I'm usually baking in the sun for a long long time. 50 miles usually takes me a little under 3.5 hours to do on some pretty hilly roads. So last summer I started itching a lot while on my bike rides, and didn't know what it was. Looked it up on the net and found that kava can make you photosensitive. Once I stopped drinking the kava for a couple of weeks, my skin went back to normal. I'll probably have to cut back on the kava this summer too. Oh well. Sure beats drinking beer.