This road leads to Kona

Yesterday I accomplisched another run on my year schedule - 12k - it wasn't my best performance (far from it), but since I haven't been running for more than 2 weeks, just to finish could be set as a "vitory".. even so, it was quite frustrating. Onde I've decided to just concentrate on my working/study load, my trainning is suffeeing big, and I just realized that sometimes you need more discipline not to train, than the opposite. It's hard to see that you're loosing power on the bike, that you're running slower than you used to, that you're loosing strenght and flexibility, but the worst is to see that you're loosing mental strenght, yesterday I really could have ran harder, but I didn't because I haven't planned to, but he worst part of the day was fighting boredom! Gee, it was really hard to see all those miles ahead, the minutes counting and the race just didn't come to an end! This took me to another question: how to train the mind, how to keep the mental focus, the strenght, the ability to shut up the voices inside our heads????
good question, no?! I'm just seeking for an answer! Anybody?