From my favourite al-Qarni's:
Citing a psychological view, living a happy life is a fine art entailing 10 things:
1. Do something you love, whether work or hobby
2. Be physically healthy as it is the spirit of happiness-eati, drink , exercise regularly and avoid bad habits!
3. have a goal in life as goal gives you motivation and energy
4. Take life as it comes, and accept the bitter and the sweet
5. Live in the present, with no regrets of the past and no anxiety for tomorrow that has not come yet
6. Think hard of any action or decision and do not blame anyone else for your decision or its consequences
8.Make smile a habit, be cheerful, be in company with the optimistic people
9.Strive to make others happy and you will be happy
10.Make the most of occassions of happiness and joy, and regard them as necessary to renew your own happiness.
Allah burdens not a soul except [with that within] its capacity... (2: 286)