If only some people would listen to what Jesus says in v36 then we could be spared those who are forever predicting when He will return. Look, when we are all called to give an account one question that God will not ask of us is "did you get the date right?"! He will ask did we love Him, He will ask did we love our neighbour, He will ask did we help the church fulfill the great commission.
Jesus says that in the time just before the end life will be going on as normal. Then Jesus tells is "because you do not know", keep watch. So we are told to be always ready for His return.
And how do we get ready? By looking for signs and trying to work out exactly when it will be? No! We get ready by doing the Lord's will. By caring for the poor, by preaching the good news, by building up the church, by being witnesses for Jesus, by doing His will.
We prepare for His return by doing His will today.