I do most of my conditioning these days with kettlebells, either doing complexes or just timed sets of swings. Currently, I'm mostly doing: 15 seconds swings / 15 seconds rest Work up to 10 minutes of that, then start mixing in a heavier bell one set at a time until the heavier bell replaces the lighter one for all sets. Then repeat.
Barbell/kettlebell complexes can be endlessly varied: http://70sbig.com/blog/2014/11/chalk-talk-11-barbell-complex/
Or, just burpees. You can do descending sets: 10, 9, 8, 7 ... 1, with a fixed 30-60 second rest in between. If you want to really hate life, superset the burpees with dumbell/kettlebell swings or snatches.
Dan John's "The Eagle": from http://danjohn.net/2011/06/the-four-steps/