You should not boast about what you will do in the future, because life is transitory. Instead, you should plan to do whatever God wants you to do, because boasting about what you want to do, rather than considering the will of God, is sinful.

James 4:13-17

13 Some of you are arrogantly saying, “Today or tomorrow we will go to a certain city. We will spend a year there and we will buy and sell things and earn a lot of money.” Now, you listen to me! 14 You should not talk like that, because you do not know what will happen tomorrow, and you do not know how long you will live! Your life is short [MET], like a mist that appears for a short time and then disappears. 15 Instead of what you are saying, you should say, “If the Lord wills/desires, we will live and do this or that.” 16 But what you are doing is boasting about all the things that you arrogantly plan to do. Your boasting like that is evil.

17 So if anyone knows the right thing that he should do, but he does not do it, he is sinning.