Can you suggest any ways to massage the back easily?

Electric massager. In the USA, Homedics makes a back massager called the Shiatsu vibrating massager with heat, It is a small pillow that you can put behind you in bed or sitting in a chair. There are actual massaging balls inside that rotate. By adjusting how much you lean back on it, you can control the intensity of the massage, It is quite helpful and convenient. There may be others as good but I tried this one.