I have always been a fan of Sealfit site and their workouts...
Here is a taste of a Sealfit 52 hour camp.
Think of the place your mind might be in during some of these activities...and compare to some intervals or training sessions you might be doing at this time...maybe indoors? maybe in the cold?
Click on the link below to watch the video. If the link doesn't work I would highly recommend subscribing to the Crossfit Journal, great information for an amazing $25.00 a year.