Remember, the key here is to zero in, which means we're not going to give a general answer like, "I will strive to do good and resist temptation." No, that's not going to do it. At this point, you need to look at your day, your agenda, your plans for that single day, and set actionable goals to serve God in specific ways based on your daily schedule. For example, let's say your reading and meditation this morning involved a passage about praise, and the Lord laid it on your heart that you need to worship Him more. Then, you look at your daily schedule and find that many of the things on it are things that cause you to grumble and complain. Right there, you can stop and say, "I am deciding right now to find something to praise God for during these tough spots in my day. I won't gripe or whine but will keep my heart focused on God and how worthy He is of my praise."
Or perhaps you look at your schedule and see that you're expected to spend the majority of the day around someone who gets on your nerves. Decide that you're going to do your best (God working in and through you) to show the love of God to that person and to bestow grace on that person even though you may not think they deserve it because you are reminded that God shows you grace each and every day when you don't deserve it.
As a final example, I'll share with you what the Lord laid on my heart Sunday morning during my optimization. He's been working in my heart about giving more and expecting less, so Sunday morning, as I looked at my busy day, filled mostly with church activities, I made a decision. I was going to serve the Lord with gladness, giving unto others as much as I could and expecting nothing in return. Anytime during the day that I began to feel overwhelmed or grouchy, the Lord brought to mind my goal, and I thanked Him and continued the service without ill feelings. The difference was phenomenal, and it felt so good to do for others with a right spirit instead of "grudgingly or of necessity." (II Corinthians 9:7)
I don't know what your days may hold, and I can't say what the Lord will impress on your heart. But whatever it is, be specific. The more specific you are, the more likely that goal will stick with you throughout the day and be imprinted on your heart and mind. And don't kill yourself trying to come up with something. Honestly, I can't think of a single time when I looked at my schedule and God didn't immediately point out some area where I could "zero in" on my service to Him. The process takes a couple of minutes, but the impact will last throughout the entire day.
Philippians 2:12 tells us, Wherefore, my beloved, as ye have always obeyed, not as in my presence only, but now much more in my absence, work out your own salvation with fear and trembling. This passage is not saying that we have to work for our salvation. It is saying that God has done a good work in us, and we need to let it work its way to the outside so that others can see. In other words, we work because we're saved. Zeroing in is taking the message that God put in our hearts and putting it into action throughout our day. It's good to know the things of God, but it's even better to do them. That's what this step is all about.
In what specific ways can you serve God today?