The secret to fighting long battles is to pray and ask God to give you strength for the day each morning.
This is because breaking down a longstanding problem with no end in sight into a series of 24 hour challenges makes it easier to manage.
Focusing on dealing with the challenges presented each day also enables you to deal with them better than if you try to focus on all the challenges you will face until the end of the year.
Jesus taught us to pray, "Give us this day our daily bread" (Matthew 6:11) even though He knew that we have to eat tomorrow and for the rest of our lives.
Therefore pray, "Give me strength to fight and grace to persevere today" even if you do not know when or if the battle you are facing will end.