I'm usually critical of public awareness campaigns and service announcements. DARE is one of the most oft-cited examples (in elementary school, I became aware of drugs I never knew existed, like Angel Dust and Ecstasy, from the program, and even recall a couple of kids wanting to realize those drugs' effects having just then heard about them). AIDS awareness initiatives serve to portray those who're HIV-positive as sympathetic victims of a malicious virus, like various strains of influenza, that must be cured through antivirals before it hops off of those infected and onto you, rather than as the result of irresponsible behavior that, if moderated, would sound the death knell of the virus.
Those are a couple that strike me as possibly being counterproductive, but the vast majority simply seem ineffectual. Often, they tend to approach the subject too methodically, as in "X number of drivers were killed on State's highways last year while driving under the influence. Don't become a statistic," says a no-nonsense Highway Patrolman with his arms crossed on his chest, instead of the brutal sounds and images of an alcohol-related crash and the desparate ululations of the victim's mother after the fact.
The people who are able to reason abstractly enough to sense just how many 'X' is, and the costs associated with that prodigious number, are not the ones who need an public service announcement to inform them that geting plastered and then cruising down the interstate is a bad idea.
That said, the current initiative being executed by the Kansas Health Foundation is one of the best I've heard. The radio ads feature run-of-the-mill conversations between people who nonchalantly decide to do things like go with mustard instead of mayonnaise, or zip up the stairs instead of waiting for the elevator, followed by a James Earl Jones clone saying, "You don't have to change everything. Just change something."
The conversations sound candid, the tone is not didactic, and the goal is not overly-ambitious. The suggestion to listeners to make a minor switch here and another there in the course of their daily routines is universally applicable, rather than only to a niche audience.
Another persistent criticism of these initiatives is that their effectiveness is difficult to measure, and I've nothing to answer that in this case. My relative approval (Generally, I'd rather state tax dollars not be spent--or collected in the first place--for this sort of thing) is based on the fact that it has induced me to make a few minor changes for the better.
After working out in the mornings, I usually slurp down three bowls of cereal. It used to be one bowl of Total and two bowls of some sugary kids stuff. Now, two bowls of Total and only one for splurging. It's become cocoa, water, and the microwave instead of chocolate on the weekends. And I've abandoned reservations about running up stairs two or three at a time and coming down them by grasping the handrails and propelling myself over as many at a time as is physically permittable. To avoid stuffing down more than I should, I've shuffled my recreational time around a little so that I engage in my favorite activity right after dinner. No, don't waste time preparing another sandwich, man, you're squandering precious playing time!
If living more healthily is something you've wanted to do but haven't acted upon the desire for whatever reason, this is an approach you might try.