INSANITY

Oh, I thought you needed a checkup from the neckup.  My bad. 

Highly recommended.  You use your own body weight.

You can do it anywhere, without any weights, or gadgets.

I tried it and it dang near killed me.  That's what happens to you when you hit your 40s.  Enjoy your youth!

My son does a few of the workouts from time to time and loves them.  I think they really help with explosiveness, speed and overall fitness.

My son also likes the Plyometric and Yoga workouts from the P90X series.

I did Insanity for awhile and enjoyed it, although after the 3 months I found that I did not gain much strength or explosiveness.  I think it is great for cardio and losing some fat quickly. But the body tends to plateau after the first 4 weeks.

What I recommend to athletes is athleanX (athleanx.com).  Life-changing for me.

We implemented it with our program and have seen crazy good results. I think the guy who runs it is legit (he is the personal trainer for David Wright after all and was the Mets strength and conditioning coach for 3 years) and has a "no BS" approach.  It is all designed for athletes, not just adults who want to lose some weight.  

You do have to pay for it, and you do have to use equipment, but not a ton. 

I also would recommend doing a Youtube search of "athlean x" because he posts weekly videos with hundreds of workouts, tips, etc.