It is important for folks to know why Tim Ferriss' "5K to 50K" training program is mostly impossible for the average reader.Or virtually any reader.
First, the program is (by my estimate) about 60% Crossfit, 30% running drills, and 10% long runs. Anyone who is not familiar with Crossfit will not even be able to decipher the program, let alone attempt it. Here is an example of one workout: "Tabata row 20:10 x 8," which translates into "Hop on a rowing machine, row full speed for 20 seconds, then row easy for 10 seconds, and repeat 8 times." Another example: "Box Back Squat: 10 x 2 on min w/ 80% 1RM" which means, "Do 10 sets of 2 reps on Back Squats, hitting a box, using 80% of your 1 Rep Max weight." And the program is 12 pages of Crossfit shorthand which is never directly explained.
Second, the program assumes you have access to not only a serious gym which includes squat racks, rowing machines, chin-up frames, jump ropes, boxes, and plenty of weights, but also a track or some place you can perform sprint drills. You are also expected to have fairly excellent working knowledge on a multitude of complex power lifting moves, which few people understand, let alone have perfected. Some examples include: good mornings, dead lifts, front squats, back squats, power cleans, presses, push presses, and kettle bell swings. If you have never done these exercises, they are not likely to come naturally. And practicing bad form with them is likely to do more harm than good. Seriously. Like, pulling or tearing muscles. Damaging your spine. These are not simple exercises, but Tim thinks you should be able to hop up and start cranking them out.
Third, the program assumes you are in PHENOMENAL condition already. It expects you to be able to do 150 double-unders on the jump rope (where the rope passes under you twice with each jump) on Day One. The program expects you to do 45 kipping pull-ups on Day Two. It expects you to do three dozen Thrusters with 115lbs over your head by the end of Week One. And that is where you START. Not the final week, but the very first week of the program.
After discussions with a dozen very athletic friends, exactly NONE of them can do one double-under with a jump rope, let alone the 150 suggested on Day One. Exactly NONE of them can do more than half a dozen pull-ups, let alone the 45 suggested on Day Two. Exactly ONE of them knew what a kipping pull-up was. And exactly NONE of them knew what a Thruster was or would be likely to do three dozen of them. And these are very athletic folks that compete as hard as they train and have years (if not decades) of experience each. But the 4HB program suggests (and Tim himself has said in interviews) that "anyone" can do it, becoming "effortlessly superhuman."
In short, NO ONE other than a very avid Crossfit enthusiast is going to have the vocabulary, skills, or strength to even attempt Tim Ferriss' program.
To think that the typical reader can go from doing little, if any exercise, to completing each of the workouts for twelve weeks is the height of egotistic aloofness and shows a complete detachment from anything even remotely resembling reality.
And yet, Your Humble Narrator is going to attempt it...