If any of you have heard of a "runner's high"...and have never experience it...and want to...the trick is a very easy start and then slowly settle into an effort level that is approximately 70-75% of your maximum. This is a lot easier effort than you think it is. A heart monitor can help you find it...so that you know what it feels like...or you can just go slower. You can't get into the nice flowing "zone" if your body is overly stressed.
Many cannot experience a runner's high because running is too hard for them. They cannot run without exceeding 70-75% effort. It's no wonder many people don't like running. It's because they should be walking...or combining walking with running instead. Folks need activities they can easily handle until they develop the capacity to handle more...if that makes sense.
Then...3 rounds of the following:
3 x Hexbar deadlift (220lbs)
12 x GHD sit-ups (snappy)
12 x pull-ups