If you have stiffness and tightness in the back in the morning then you need to work on improving the flexibility of your low back and hips and strengthening the core muscles to take some of the tension of your low back muscles. To relax your low back and hip muscles start engaging regularly in self myofascial release with a foam roll of the low back, glutes and hip flexors, these muscles typically become excessively tight in most people who sit for their job. Foam roll each of these areas for 30 seconds per area especially focusing on any sore spots or trigger points. Some common stretches for the hips, hip flexors and low back include camel/cat, cross leg stretch hip flexor stretch and 90-90 stretch.
To perform the camel/cat stretch position yourself on the floor on all fours with your head and spine in neutral alignment. Gradually, and slowly start alternating between arching and flexing your back creating the shape, a camels hump and a cat arching their back. To perform the cross legged stretch lie flat on the floor with your back and shoulders flat on the matt and your legs extended straight out, and arms straight to your sides forming a T shape. Raise one leg cross it over the body so that your back and hips must rotate until you feel a stretch in the spine and upper leg. Keep your shoulders on the matt at all times and keep your head, and neck relaxed and flat on the matt at all times. To perform the hip flexor stretch, kneel on the ground on one leg with your other leg out in front bent at 90 degrees. Keep your torso completely upright core engaged spine in a neutral position. Shift your weight forward while at the same time contracting your glute on the same side as the stretched hip flexor, and extend the same side arm over your head. Shift your weight forward until you feel a stretch in the hip flexor region hold this position for 30 seconds, repeat on the other side. To perform the 90-90 stretch sit on the floor with one leg in front of you and the other leg behind you. Take the leg in front you and fold it so it is bent at a 90 degree angle with the heel towards the body as if crossing your legs while sitting. Sit down into the stretch until you feel a stretch in the glutes and upper hamstrings area. Hold for 30 seconds per side. To strengthen the core perform the prone iso ab hold, lie face down with your elbows placed on the floor, body parallel to the floor with core engaged and spine in neutral alignment. Hold this position for 10 seconds then relax, repeat for 8-10 repetitions.