IAG,
Yes, it seems like the magazines are probably the best for motivational purposes. Each month they have a catchy cover, nice pictures to inspire you, and some current event stuff. So that in itself will help out alot.
For sound advice though, i would search for books by reputable authors or institutions. For most of you who are afficionados to fitness, I would recomend pickin' up a fitness/personal training certification. Even if you don't want to work as a trainer, the materials are full of good info, and they will supply you with good options to continue your education. Some of them are very hard, but some of them are entry level certs that will help you out a lot.
Here are some of them:
American Council on Exercise,
IFPA
AFAA