Play for an hour in the key of E...and do it until you know it, the key of E

Played a jam not long ago. I was out of my league, way out of it. I was playing someone else's guitar, a Fender Strat, which my friend says is the hardest guitar to play because you have to pick it in the right place to get a fat tone. That was the least of my worries. I didn't know any of the 3 songs I was in on. At one point the lead guitarist just looked at me as shouted, "play", when it was my ride.

I played. I wasn't really playing anything, not improvising, just moving my fingers as fast as I could more out of fear than faith...I wasn't musical, wasn't listening, wasn't having fun.

I asked the lead player afterwards what I needed to do. He asked me, "do you play your guitar every day?"
I said, "Yes." Truth too. Then he asked me, "Do you practice an hour or more every day?" I said, "No".

Next day I played for an hour only in the key of E. My left arm went numb. I got worried. Backed off to 30 minutes the next day, still in the key of E. I'm still working 20-40 minutes a day, usually in two sessions (or else my left arm goes numb) and I'm still playing in the key of E.

Join me in the key of E. Practice, Practice, Practice. I want to be able to say something on the guitar that springs from my heart of hearts.