The Warm-up!

A good warm up is the key to a successful workout. In general, the shorter the workout the longer the warm-up! The quicker or more explosive you are while doing something under load the higher the potential for disaster/injury. High acceleration = High Force (F=m*a) especially at high mass/weight. So if you are going for a slow jog you probably don't need to warm up the muscles because the jogging is such a low stress/shock on the system that it will essentially be your warm-up. However if you are going to hit 6x50m sprints then you are probably going to want to do some amount of warm-up - like a light jog, then a faster jog, then a slow run, then a fast run and finally a sprint at ~90%. The same goes for heavy lifting do a few reps at 45% (5reps), 65% (3reps), 85% (2reps) before attempting your first lift (100%). The warm-up should not be too hard and essentially just there to get your muscles full of blood and loose, allowing you to move all your joints/limbs through the full ranges of motion needed in the exercises you will be doing. Do the warm-up at a comfortable pace but don't take to long, save some time for the actual workout!

My favourite way to warm-up is as follows:
1.) 2 minutes skipping - singles (so easy to do, very little range of motion, very low effort but get the heart pumping)
2.) dynamic movement (arm and leg circles, toe touches etc. just get those limbs moving in a full range of motion)
3.) basic body movements (air squats, pushups, situps, pullups, back extensions - pretty basic stuff, nothing fancy but it warms up the muscles in a large range of motion)
4.) the sticking points. I only use static stretching on anything that is super tight - hips, and ankles are the big ones here. The preferred method to loosening up the hamstrings, glutes and quads and pretty much everything else is PNF. *Note* most static stretching should be done post-workout as it can have a detrimental effect on performance if done pre-workout (hips are usually only exception to the rule).
5.) If needed foam roller on the sore areas
6.) raise the heart rate a bit (all that stretching can lower the heart rate and you start to get cold, you should have a slight sweat on before you start the workout) I like to do skipping -Double Unders.
7.) Practise - go through any movements which you are unsure of or rusty that are in your workout. If it is a lift do reps with the bar and then 45%, 65%, 85%.
8.) Mentally focus on the task at hand - take a minute or two to rest and think about how you will complete the workout, close your eyes and image yourself doing each exercise to completion until you are finished
9.) Grab some water to rehydrate, and chalk up.
10.) Kick butt on the workout.