Doing God's will is easily said than done. If you see clearly that there is a chance to help someone or bring the person closer to the Lord, then it's no problem. But if there is an opportunity, say, for you to make some money, it might be difficult to discern whether you should take advantage of it or not because the attachment to money and material things can easily surface and cloud your mind. My guideline runs like this. If what you are thinking of doing is going to affect your prayer life, your present work in serving God such as what you do through your church ministries, and/or any evangelization your engage in on your own, you should not do it no matter how strong the temptation. Our union or personal relationship with God must be preserved. It should only grow stronger, not weaker.