At 8 a.m. my smartphone alarm goes off, nearly jolting me out of bed. It displays a short message: “Aim for 30 minutes of exercise today.” Craving another hour of sleep, I duck under the covers, but immediately that thought is replaced by another: “You know, this app actually has a point.” Five minutes later, I’m in my sneakers and out the door.

Juice is one of the apps I downloaded as part of my three-week long experiment to see if my smartphone could help me change my bad habits. I wanted to be fitter, more energetic and more social. I also wanted to eat better and stop spacing out on what I wanted to see at the movies.

There was no science to my selections, although they did have to meet some criteria. They had to be new-ish (i.e., launched in the past year), well-received and strike me as intuitive to use. They also had to be cheap because I’m on a budget.