Ships don’t sink because of the water around them; ships sink because of the water that gets in them.
Don’t let a tough evening commute ruin dinner time with family. Don’t make a snap decision because the stock market had a wobble. Don’t relive mistakes and past interactions, or get anxious about things that haven’t even happened. Don’t let the past or the future leak into the present.
Build watertight compartments by focusing on the task at hand. Do you have a plan? It doesn’t have to be a 5-year plan. Maybe the plan is to wake up, make a cup of tea, and get an early start. Get going and accomplish the mission. Then make a new plan and do that.