Verily I say unto you, This generation shall not pass, till all these things be fulfilled (Matthew 24:34).
The Greek word that Jesus uses here is the word “genea” which is most often translated generation. In the context of the entire Olivet Discourse the “all things” includes everything from the beginning of sorrows through His second coming. Since a generation only lives so long, Jesus provided a time frame by which to answer the disciples’ original question: “when shall these things be?”.
The oldest verifiable person in recent times was Jeanne Calment from France who was born in 1875 and lived to be 122 years old. The list of the verified 100 oldest people reveals that several people have lived to be over 115 years old which means that approximately 120 years could elapse from the beginning of sorrows until the second coming of Jesus Christ. If WWI marked the first sign then Jesus could return around 2034!