Doing my best is not necessarily studying hard for a test or doing my best in something or preparing. Doing my best is seeking God. Doing your best is doing your best to seek God and He gives you the courage to fight and to be still. You only need to be still and seek God for any battle. That and obeying God. That is doing your best.
Doing your best is not doing your best in something, it’s not studying or preparing. It’s doing your best to seek God, to obey God, and, when the time comes, to fight, to take the action. To spend more time seeking You than doing anything that prepares me. It’s like having only two swords among the twelve disciples (Luke 22:38), only one-sixth of the time should be spent on direct preparation and five-sixth on seeking God. Life is not really about preparing but on seeking God.