Apply the above concept to your hips. When you sit, your hips are in a "flexed" position. Therefore, the muscles that flex your hips are in a shortened state. You probably spend at least a third of your day sitting down. Think about how much time those hip flexor muscles stay shortened. A lot. Over time, they become tighter and tighter until you look like the old man in the picture. So unless you want to look like that, perform the stretches shown below.
A pinched nerve is an uncomfortable condition that may cause shooting pain, tingling, and discomfort, particularly if it occurs in your back, spine, or hip. A pinched nerve occurs when too much pressure is applied to a nerve by surrounding bones, muscles, or tissues. The pressure interrupts proper nerve function, causing pain, numbness, and weakness.

To make a long story short, I have been experiencing acute pain in my right hip as a result of driving so much. It does not really hurt while I am driving, but when I try to get out of the vehicle, the pain can be quite severe (making it almost impossible to walk for a ten seconds or so). In fact, it had gotten so bad that I was having trouble after sitting period (i.e. in chairs, etc). I was beginning to fear that I was going to be fundamentally disabled unless something changed.
Grade II (moderate): A larger tear in your muscle that makes it difficult to move and causes a moderate amount of pain, especially when you move the affected muscle, swelling, and tenderness. You may have 5 percent to 50 percent loss of function and you may be limping. You can't go back to sporting activities until the tear is completely healed. These injuries can take anywhere from a couple weeks to a few months to heal, depending on how bad they are.