If you have already been training for a while, the main reason for your lack of flexibility is actually not the fact that you haven't stretched enough or that you are naturally inflexible. 

The main reason why people have tightness everywhere in the body is simply the fact that they are weak. 

You see, flexibility is a form of strength. 

When you train all of your muscles properly and sufficiently in their full range of motion, the muscles will become quite flexible by proper training alone.

The reason why you don't have any flexibility issues in your elbow joint is that everyday you keep using your arms to drink, pick things up and do chores. 

As a result, you not only have the full flexibility but also plenty of mobility and strength in your elbow joint (biceps and triceps). You have this despite you have never stretched the elbow joint. 

In everyday life, it's not as common to use your hips as freely as your arms which is why they get stiff and tight over time. That's why we need training.

Stretching is good and recommended but the main reason for your inflexibility is not the fact that you haven't stretched enough - the main reason is that a large portion of your muscles are weak and under-developed.

Just by doing proper training that targets all the muscles of the body, you should notice massive improvements in your flexibility. 

A lot of people think they train their legs properly but they usually stick to one or two basic exercises. These basic exercises are excellent but they are not sufficient to target all areas of the legs and hips.

When someone has big legs but his hips and legs are tight, the main reason is the fact that the person has plenty of imbalances and under-developed areas in his hips and legs.

The person's major muscle groups may be strong and mobile but the smaller muscles such as the hip rotators, inner thighs and many parts of the glutes are probably weak.

It's time to throw away the excuses such as "I am just naturally not flexible" or "I just don't like stretching". 

Everyone is naturally flexible AS LONG AS all of their muscles are healthy and have the necessary baseline strength. Some people have hypermobile joints but the standard good level of flexibility is a birthright that has been blessed for us all.

If you hate stretching - you don't have to do it although it is beneficial. The most important thing is learning how to train the body properly - when you do this you will develop relatively high levels of flexibility without doing any stretching.

The reasons why most training programs or styles do not develop flexibility (or mobility):

The reality with our programs is that almost all of our exercises develop mobility. Why? Because our methodology is on point. As a result, mobility is not supplementary or secondary training.

When a person focuses only on lifting heavy and often does this with a poor form (especially in our standards), the repetitions do not properly develop movement quality.

Movement quality mainly comes from mobility and mobility is just strength in every portion of the range of motion. 

A lot of people may use full range of motion but they lack absolute control in that range of motion - this doesn't work and doesn't develop mobility nor movement quality.

To fully develop a muscle you need to know how to target the muscle. You need stabilization and muscle refinement principles for this.

Once you know how to target a muscle, you need to have patience and mindfulness to perform the repetitions with slow tempo and controlled execution where unnecessary momentum has been eliminated.

Training like this develops strength, flexibility, active mobility and movement quality. This should be the baseline and foundation for every other type of training such as power or speed training.

Moreover, when you have the best exercise selection, this style of training also ensures the health and structural balance of your body so no area gets neglected. 

This is literally the step 1. The foundation for everything. Lifting heavy or doing power training is already way ahead of this step. You are not only physically weaker but also more fragile unless you master this first step.

The fastest way to increase your muscle size, strength, athletic ability and even power is to take care of this first step because many of the muscles are under-developed and as a result respond to training incredibly well.

The number one reason why we LOVE to work on our weaknesses is that behind these weaknesses are all the significant gains anyone can make. If you only work on your strengths, the improvements are marginal at best.

What you just learned is exactly what Athlete 20XX is all about.

Stay strong.