Yes, you're right. Happiness is a choice. There is a difference between happiness and joy though. Sometimes happiness depends on our outer circumstances whereas joy comes from our inner attitude.
Life has its' ups and downs, good times and bad times. If it were all ups and good times we would not appreciate the bad. This gives us a greater reason to put things into perspective and appreciate the good stuff.

Creating positive attitudes, creates a nicer environment and get better results.

Better attitude= creates more joy= a more consistent feeling of happiness.