A host of helpful new apps launched during the 2011 South by Southwest Interactive conference, many promising to improve your life in small but profound ways. There was even a site for apps to improve your life at SXSWi. These newcomers joined the legions of existing apps designed to make you a better functioning, more highly evolved individual.

If you're the proud owner of a smartphone (or a tablet or any other gadget capable of downloading an app), it can be difficult to resist the lure of these digital elves. They offer, as tech writer (and Details contributor) Daniel Sieberg puts it in his book, The Digital Diet, a means to "outsource self-control." Want to lose weight? There's an app for that. Want to quit smoking, improve your dating skills, balance the competing demands of life and work, or embrace positive thinking? Just cruise the App store or Android Market until you've found the product designed to fix your flaw. There are even apps designed to wean you of your dependency on apps: One product, a sleep monitor called Sleep Science Alarm, comes with a built-in "iPsychologist" that claims it can help users overcome their addiction to Angry Birds. Install enough of these electronic helpers on your smartphone and it becomes a kind of virtual life coach, a pocket-size Tony Robbins or Dr. Oz that alternately berates you and cheers you on. Yes, it still makes calls and sends e-mails, but it exists mainly to remind you to get a salad instead of a burger, to talk you out of driving home from the bar, and to encourage you to spend more time with the kids. It becomes your mentor, minder, and mom.

Chad Mohler, a 39-year-old college professor in Kirksville, Missouri, shed more than 40 pounds with the help of a free iPhone app called Lose It! The program puts you on a calorie budget based on your age, sex, height, and weight, then uses a database of nutritional information about popular foods to measure your intake. Eat a late-night Big Mac after reaching your limit and Lose It! will display a status update that reads "I am 540 calories over my daily budget." Helpfully, Lose It! also contains a list of common exercises so you can do penance and reverse the damage. "I usually have my phone wherever I go," Mohler explains. "If I were just tracking what I was eating on a piece of paper, I might not be able to do it as easily." With the app, the iPhone became his virtual nutritionist, without the expense of a real one. Mohler concedes, however, that it takes a special kind of obsessive to get comfortable with apps like Lose It! His wife tried it and found it too cumbersome, he says, and even he sometimes found it difficult to punch in everything he ate (the process of entering foods not already in the database can be painstaking). "If you're not dedicated," he admits, "you'll probably have more trouble."

And that's the puzzle of these apps. For all its futuristic specs, the iPhone lacks one key feature—it can't gin up willpower. Take Can I Drive Yet?, one of many programs (see also: DrinkTracker, Funtoxication, DUI kNOw!, and many more) that calculate your blood-alcohol content by tracking how many drinks you've downed. When you reach the legal limit, a red warning message encourages you to call a friend or a taxi. There's an obvious Catch-22 here: If you're deliberate enough to log each cocktail you've consumed, you're probably not the type who'd get wasted enough to need the app. Similarly, Quit It, one of the many smoking-cessation apps for the iPhone, offers only tepid encouragement, not true accountability: It tallies your days of smokelessness, congratulating you on your increased lung function and the money you've saved, and even awards you a ranking that improves the longer you stay tobacco-free. But considering how easily you can click away from the program, it's hard to see how it can overcome a force as powerful as nicotine dependency.

Okay, but if your iPhone can't improve your willpower all by itself, maybe it can enlist your friends to help. "The way our brains work, it's often easier to do something for someone else's approval than for ourselves," says Robert Fabricant, vice president of creative for the consultancy Frog Design. His firm has developed an app called Temptd that will help you meet health and wellness goals by broadcasting your progress (or lack thereof) to your friends on Facebook—a peer-monitoring approach that many other apps have begun to adopt. Frog's goal with Temptd, Fabricant explains, is to better understand how to instill a sense of "mobile willpower" in users by placing them within a system of continuous encouragement and support. You might see a flesh-and-blood life coach only a few hours a week, but your phone's always with you, which means your social network is too. If we actually respond to digital social cues—to eat and sleep better, to quit smoking, to take pills on time, to get check-ups—maybe our phones really could be lifesavers.