It's difficult but not impossible to be happy when living with pain. Pain medication can numb your mind as well as your pain, so feeliing mentally well is challenging.
Pain is distracting and can be all consuming with little space to appreciate what's good. Constamt frustration with not being able to participate fully in life is also an issue. There are ways to train your mind to deal with constant pain constructively using midfulness techniques that also help with depression.

My husband, 76, was first diagnosed with severe back degeneratiion caused from his employment. Then the arthritis, disc deterioration, etc, etc, diagnoses were made. Then within 5 years he was diagnosed with bypolar depressant syndrome. He now takes antidepressant medication of all kinds, and pain medication of all kinds, but still has back pain and is depressed and irritable 85% of the time. Maybe 15% of the time he seems like his old self, but still in constant pain. What came first, the chicken or the egg? This all started about 12 years ago and he has become an old man before his time, and has difficulty in finding pleasure in any activities. All I can do is pray for him and try my best to please him.
Any suggestions? ritam83