Everyone wants to be able to create their own happiness.
If you like to express that in Mandarin Chinese, you can consider using the phrase:
"我创造自己的幸福"
wo chuan zao zi ji de xin fu
创造 refers to create
自己 refers to ownself
幸福 refers to happiness
Alternatively, there is also a phrase that you can use:
"快乐之权，操之在己”
kuàilè zhī quán, cāo zhī zài jǐ.
This would translate to “One’s right to be happy lies in his/her own actions.