A lesson I'm learning at the moment is to trust God. That sounds a little weird, right? All Christians trust God don't they? Well, in theory, yes. In practice though, we need to learn how to apply that trust in many, many, different ways and situations. It takes a lot of time and experience to discover even the smallest part of what it really means to trust God. This is a huge part of every Christian's sanctification in becoming more like Christ.
The situation for me, in general terms, is that sometimes there are things that I cannot control and I have to just give up and rely on God for the favourable outcome. The trick is in knowing when to relinquish my responsibility to correctly know what to think, speak, and do. That is not to say that I will give up on doing the morally and biblically right thing, but sometimes it will mean making a decision between a rock and a hard place and trusting God to help. Sometimes this will mean that I learn that I have done something wrong and sometimes the end result will be a happy outcome.
Choosing the lesser of two evils, or the greater of two goods, would be a general example. A more specific example: knowing when to pursue an outcome actively, and when or how long to wait for events to be right to pursue that outcome. An example from physical training: deciding between having a rest, to recover strength, versus doggedly battling through the pain to accomplish a goal and to learn mental toughness. An example from a moral decision: In a debate, should I insist on the other person understanding and being convinced of my (hopefully biblical) perspective, versus giving up for now and continuing the debate another day and preserving a level of peace that ensures the conversation will not be shut down next time?