Jesus tells 2 stories here. In the first, He talks about a fella who starts building without committing the necessary resources to the project. When he can't finish the tower, the unfinished construction stands as a monument to his stupidity. The second story is about a king who decides to go to war with another king. He must decide whether he can commit the resources to win the fight or the defeat will stand as a monument to his stupidity. Jesus concludes with his final "if you don't...you can't" statement. If we aren't willing to give up everything, we can't be His disciples. Basically, we need to be ready to commit every resource, every calorie of energy, every moment of time and every dime of money to Jesus or our failure as His disciple will forever stand as a monument to your stupidity. This isn't really a 'count the cost' call like we normally hear taught. I.e., we must count the cost to see if it is worth it to follow Jesus, a sort of spiritual cost/benefit analysis. What Jesus is actually calling us to count or consider is whether or not we will give up everything, or if our 'discipleship' will be just a half-built tower.

Luke 14:28-33