According to a Daily Mail report the technology is being developed by the Center for Behavioral Intervention Technologies and a professor of preventive medicine at Northwestern's Feinberg School in the US, and uses information from GPS, BlueTooth and Wifi as well as other information already on the phone.
Not all users would welcome such an invasive app, and of course it's not going to be compulsory. It's also going to need a lot of tailoring to individual habits.
For example, many people would find the freelance writing undertaken by many bloggers and writers undesirable. This article is being written in a spare room in the writer's home, in isolation; clearly this isn't going to suit everybody, but a text telling me to go out and cheer myself up isn't going to get the job done.
There are a lot of variables in this - it will be interesting to see how the technology comes along.