Flexibility and mobility are important because they affect joints and the surrounding muscles, tendons, and ligaments — and the way the body moves. Soldiers need give-and-take between joint flexibility, mobility, and stability for coordinated and efficient movements as well as injury prevention. It’s important to keep the body fit for movement, especially as Soldiers train for Physical Fitness and Physical Readiness Tests.
Additionally, performing stretching and mobility exercises can promote long-term changes and improvements too. To boost and maintain flexibility and mobility, incorporate dynamic warm-ups, as well as a stretching or mobility cool-down into a regular training regimen. 
Joint flexibility — also known as range of motion — is the amount a joint can move before the surrounding ligaments, muscles, and tendons restrict its movement. That is, it depends partly on the flexibility or “give” of these surrounding tissues. The same FITT framework provided in parts 1 and 2 of this series (on cardiovascular fitness and muscular-strength training) also applies to mobility training: frequency, intensity, type, and time, combined with progression.
There still isn’t agreement among experts as to exactly how much mobility training people need. The following is a summary of flexibility-exercise recommendations.
Flexibility exercises (stretching) should be performed at least two to three days per week, but daily exercise is most effective too. Soldiers might see short-term improvements in flexibility after each session of stretching, but long-term changes usually take three to four weeks of regular stretching exercises.
Flexibility exercises should involve major muscle groups (neck, shoulders, upper and lower body, etc.). Static stretching is great for making long-term improvements in flexibility. Stretch only to the point of slight discomfort within the range of motion, but no further.
There are several different types of stretches:

Static stretching slowly elongates a muscle when exercisers hold the stretched position for a period of time. Dynamic stretching is often sport-specific and involves a joint being stretched by controlled movement through its full range of motion to lengthen and increase a muscle’s temperature. This is ideal for warm-up, and it helps improve mobility. Ballistic stretching is a type of dynamic stretch where the muscle is forcefully elongated through a bouncing motion. There’s no evidence that ballistic stretching results in injury more than other types of stretching, but whether this technique affects muscular performance is still being investigated. Proprioceptive Neuromuscular Facilitation stretching often can produce greater gains in ROM, but exercisers need an experienced partner to perform this type of exercise. Time

Probably the most important aspect of “time” is when to stretch: Dynamic stretching should be part of a pre-activity/exercise warm-up, for at least five to 10 minutes in duration. Static stretches aren’t useful as a warm-up to exercise and might actually hinder performance. A reasonable target for stretches, including ballistic and PNF, involves a three to six second contraction followed by 10 to 30 seconds of assisted stretch, which is about 40 seconds of total stretching time for 2 to 4 sets.
The methods for optimal progression are unknown, but those who have very limited mobility and flexibility should start slowly and gradually increase the length and depth of their stretches, as they feel more comfortable.
Use caution when performing mobility exercises. Done properly, they shouldn’t cause pain in joints or muscles. Never push through a personal threshold, be patient, and treat joints with care.
The goal is to prevent injury (not cause it) and contribute to overall fitness for PFT/PRT and more. If Soldiers keep up their exercise routine after the tests and continue to set goals and challenge themselves, they’ll stay warrior-athlete fit.