This may be way harder than what you're looking for considering you're more of an endurance oriented person, but I couldn't stop myself from using this as an opportunity to create the ultimate pain tolerance/ strength/ endurance/ power compettition. Oh, and this is all to be done in 4 days.
1. Overhead barbell hold for 10 minutes with 225 lbs.
2. Farmer's walk, two hundred pound dumbells for a mile.
3. 200 lb. sandbag carry up the steepest and longest incline you can find, a great test of both stamina and strength; I was sore for nearly a week after carrying my barely 100 lb. girlfriend up a steep quarter mile hill.
4. Density training a la Bryce Lane, olympic squat 350 lbs. 100 times in 20 minutes.
5. As a more endurance oriented activity, 20 half mile sprints in 2 hours, each one under 2:20.
6. Butterfly stroke in the pool for a mile in sweatpants and long sleeve shirts for extra resistance in under 35 minutes.
7. For pure power, pull 300 lb. barbell from floor to locked out overhead like in a clean and jerk or clean and push press.
8. 600 pullups in 60 minutes. Very strict, all the way down to all the way up.
9. For pure strength, a 550 lb. deadlift.
10. Tabata thrusters with 95 pounds for 4 minutes for a minimum of 12 thrusters each work interval.
11. Muscleup with 75 lbs. extra resistance.
12. one arm strict curl and press 45 lbs 100 times. I know some guy claims to be able to do this one over a thousand times, but can he do the other 11 challenges too, and do this one after all of those in a 4 day period?
If I could one day do all of these I would be proud as hell for a while, until someone like Greg Amundson came and made me look silly by doing the entire thing in a matter of hours.