Instinctively, we hate leaving what we know and love; we intensely dislike bereavement and death is a real enemy (1 Corinthians 15:26).  However, if we know that leaving one job will enable us to do a job which suits our gifting better, then we are glad.  No parent likes children to leave home, but knows that unless they go, it will be impossible for them to mature and fulfil their vocation.  Jesus was not leaving the disciples because He did not care for them; He loved them deeply: but like a parent knew that they had to grow up spiritually.  Anyway, He was going to prepare a place for them in heaven and promised to return to collect them and take them to His heavenly home (John 14:1-4). But the greatest reason for His departure was that He loved the Father and was returning in obedience to His command.

Jesus knew that the disciples were growing anxious as He spoke about His death and return to the Father, so He wanted them to know that His leaving would bring great blessing.  For example, if Jesus was still on earth, the apostles would never feel able to take the responsibility He has appointed them for (John 15:16).  If Jesus was still physically on earth, He could only be in one place at any time … but by leaving and sending His Spirit, He would always be with all His disciples wherever they are, all the time (John 16:7).  

But before His ascension, Jesus had to die.  The disciples needed to understand that although Satan wanted to destroy Jesus, it was the Father - and not the devil - who was in command of the crucifixion.  His resurrection proved that (Romans 6:4).  Jesus went to the cross willingly because He loved the Father and was determined to do His will (Luke 9:51; John 6:38-39).
 
Although it is difficult for us to look forward to a future we know nothing about, Christians should be glad to accept and engage with the future, because the Lord is in command of every detail of every tomorrow.  Often, we may be called to step out in faith, even though we cannot see the end from the beginning (Hebrews 11:8) … but that does not matter because Jesus does!  Faith will enable us to bear the pain of leaving the past, trusting that the future will be good - because Christ is in charge.  There are times when it seems that the devil is closing in to kidnap us away from God’s purposes for our lives … that is the time to be decisively obedient, like Jesus was.  Obey and do not delay!  Do not keep looking back like Lot’s wife (Luke 17:32-33), but keep trusting Jesus and obediently press on towards Him (Hebrews 12:1-2 ; Philippians 3:12-14).