Dynamic Warm Up
The warm up is the most important part of any workout. Let me say that again: the most important part of every single one of your workouts is the WARM UP! Do not skip it. Do not rush through it. Plan ahead and get it in. It sets the stage for the work that is to come. Without it, you risk injury, and your body will get less value from the training.
The following video quickly outlines a dynamic warm up you should be doing before all biking, running, and strength training, if that's not following a cardio session already.
Each one of these should be done around 20-30 seconds in length, at a minimum. A good visual for that length is a full baseball court. They are shortened in the video so you can see them all.
Walking High Knees
Walking Butt Kicks
Hurdle Walk Overs (Keep your knee high & move through your hip while your upper body stays facing forward.)
Hurdle Walk Overs Backward
Knee Huggers to Quad Tug
Soldier Walk (Notice the slight crunch from the torso, into the leg. The goal is not to get the leg as high as you can, but to keep the leg straight to actively stretch the hamstrings.)
Toe roll ups with overhead reach. (Reach from your lats and open up your ribcage).
Walking Lunges (Do these in place if you have knee trouble.)
Side Lunges (Remember: weight over your heel. The goal is to stretch through your groin, not depth.)
Leg Swings (Video below) The goal on these is to make sure you're moving from the hip and mainly glutes, not by rocking the body back and forth.