Tight hamstring can be due to several factors.  It can be caused by your posture.  If you have exaggerated pelvic tilt then tight hamstring and lower back pain would be the result.  Another cause is that you really have short hamstring physically.

As a result, tight hamstring can bring injury.  It affects movement and can create back and knee pain.  It also affects posture which can lead to many other injuries and pain. Nonetheless, you won’t look good with a bad posture.

Here is a stretch you can do every morning using flex-band.  Hamstring mobility can be better with these stretches.  Now you can do more strenuous tasks like running, jumping and leaping. Wrap the resistance band around your right foot.  Then straighten your knees.  Use the resistance band to pull your right foot.  Count to 10 the repeat for 3 times.  Do the same with the other leg.

Make this stretch a challenge by looping the resistance band around your neck and the sole of your foot.  Straighten the knees.   Pull the resistance band over your head.  If you have very tight hamstring, it will be hard to do this.  Your goal is to reach this stretch.

Stretch the medial hamstring by mobilizing your hip from the sides.  Do the same loop on your foot and stretch the sides of your hamstring.  when you do one side (left), do not forget to stretch to the other side (right).

My personal choice for a resistance band is flex band by Merrithew.  I like to buy quality band from a quality brand.