Just to add to Whistle Stop, Mark Clark and Brendy mentioning of the pain experienced as a beginner.....
I have found it helpful to play until my hands are kind of sore but not in pain. That is when I stop.
I am not speaking of painful chord positionings, I am referring to just playing for a period of time until my hands get tired. I figure if I stop before I am feeling pain, then I have less of a chance to develop an injury. So instead, I make it a point to break up the times I play. I play until my hands feel tired, then I put down the banjo and pick it up a bit later. I also believe I get a lot more playing time in this way and it suites my daily routine.

Bonnie