Do I consciously need to think "I am doing this to please Allah" while doing a good deed? Or is the good act, when done with sincerity, itself sufficient as a means to please Allah?
Bismillah
Thank you for your question. You don't have to think out the words before doing the act, but you have to know you are doing it for the sake of Allah. Thinking out the words is a way in which some people make clear to themselves what they are doing. Sincerely carrying out an act for the sake of God is sufficient without thinking out the words. It is also recommended to start out those works with the bismillah.
May you always be successful