Jamming, Kidapalooza, Lollapalooza 2013 by Eric Gravengaard, licensed under (CC BY-SA 2.0)
I have a rule that I enforce on myself and which I encourage students to adhere to. That rule is, for every 10 hours I practice, I must spend at least 1 hour jamming with others.
Jamming with others is not only good for your musical soul, but will make you a better all round guitarist, and it feels damn great too.