This goal has the following fine print specified by katerena:
This combined duolingo and whatever else I am doing. So, the following are all "1 lesson:"
* 1 full unit on duolingo
* 3 units reviewed on duolingo (or 2 units reviewed, if one of them is a perfect 20 and the other is a respectable >=10)
* reading a German book until I just can't anymore
* 30 minutes of talking German (ie, at a language meetup)
* 2-3 hours of "immersion" - being in a public environment and actually participating as much as possible