Hamstrings, the bane of lower limb muscle injuries at all levels of sports. Factors include age, previous injuries, and biomechanics. Furthermore, the recurrence of injuring your hamstring again is remarkably high.
What is your prevention management plan for healthier hamstrings, so you can become a better version of yourself for your CrossFit? 

The Anatomy of the Hamstrings. 

The hamstrings are formed by three muscles, which are located on the posterior (back)  thigh. The biceps femoris, semimembranosus, and semitendinosus. They are a two joint muscle group.
What does this mean?
This means the hamstrings acts on two joints of the body: 
1. They allow extension of the hip. 
2. They allow flexion of the knee.
How is this applicable to your Crossfit? 
If you are lowering into the bottom of the squat "the hole", then you will be using your hamstring muscles. If you are running you will be using your hamstring muscles, if you are rowing, you guessed it, you will be using your hamstring muscles.

The important stuff What can you do?

Mobilise the hamstrings using a barbell:
Put the J hooks at a height in which when placing the bar onto the J hooks, you should be able to step over without hurting yourself and you will be able to rest your hamstring muscles on the bar. Next, you are going to contract the muscle, by moving your leg up and down (flexion and extension).
Work your way back up towards the top of the glutes. Do this for a period of 2 minutes on both legs. 

Nordic Hamstring curls: 
Eccentric stretching the Hamstrings, research has mixed reviews on whether this helps. However, there is no one method that fixes all. Therefore, Nordic hamstrings curls have been implemented into this MotionPlus Monday, because there is no one size fits all. How to perform this;
1). Kneel on the edge of your bed or on the floor with an ab mat underneath your knees.
2). Secure your feet by having a partner hold onto your legs.
3). Lower your torso towards the ground, as slowly as possible.

This is hard, and when your hamstrings can no longer support your weight, you will find yourself falling to the ground. Remember to catch yourself in a push-up position. Over time, you might actually be able to control the entire descent.
The amount of reps you do, is depending on your level of competency.

Single leg Hamstrings brides:
This activity is performed with either leg placed onto plyo box, chair or exercise ball with the knee flexed. The other leg being held in the air, and the pelvis is then lifted off the ground, to form a bridge position. This activity places the direct demand on the hamstring that is in contact with the plyo box, chair or exercise ball, to contract to support the body during the bridge. The pelvis is then returned to the floor to complete the repetition. To increase the demand on yourself, use an exercise ball (swiss ball) and push the ball slightly away from you, then pull the ball back with your heel towards your glutes.

Remember if pain or the issue persists go see your healthcare professional and get it sorted.  

Take home message:

There is no one way in which you can rehab an injury, but find the method that works for you.