I carry a 35lbs piece of slate and a lump of coal with me to record my workouts.
I use roman numerals to keep count of my sets. To track my weights for each lift I use a simple weight to # of goats conversion. One goat (8 month old female) weighs roughly 45lbs. So if on set one of squats I did 405lbs (9 goats) for 5 reps, then set I. equals 45 goats.
When I get back home to my cave I scrawl all of my workout on to the ceiling. This keeps me from using up to many pieces of slate. I then proceed to have my post workout meal of goat meat.