If you spend a lot of time in a seated position (i.e desk job/driving) then it’s quite likely that you will have tight hip flexors.
These are the muscles responsible for bending at the thigh/hip. So if you are constantly sat with your hips bent these muscles will constantly be in a contracted and shortened position, so of course they will be tight!
I would recommend taking regular breaks and having a walk around and a stretch in an attempt to remedy this tightness, along with a regular massage of course!
The bottom picture below shows what a hip flexor stretch looks like.
In the top picture the models knee is line with her hip. If you have extremely tight hip flexors you may feel some stretch in this position, but as this is the position your hips would be in when you are standing you probably won’t be stretching your hip flexors very much.
It may remind you of the more commonly seen quad stretch, which is similar, but done in a standing position.
Only one of the quadriceps muscles crosses the hip joint (the rectus femoris) and this is why simply doing a quad stretch won’t quite target the correct area.
If you really want to target the hip flexors you must move your hip in front of your knee. This then takes your hips into extension, which is the position to best feel the stretch.
You can deepen this by lunging forward onto your front leg, pushing your hips forward and leaning backwards (from the hips) slightly. You can also intensify this by squeezing your bum muscles (gluteals).
Your gluteals are functionally opposite to your hip flexors and when one muscle contracts the opposing muscle must relax. This is called reciprocal inhibition.
If you would like further information regarding stretches I can provide this as part of the aftercare you receive at the end of a massage treatment.