I will ask the Father, and he will give you another Helper, to be with you forever,
(John 14:16) 

Jesus has been talking about his impending departure, Judas' betrayal, Peter's denial. The disciples are understandably concerned - it looks like the wheels are falling off this mission. Jesus comforts them by promising the Holy Spirit.

The Holy Spirit is a Helper which is great news because we need help.  He helps us grow in love and obedience. He is our Advocate, our Comforter our Counsellor. This is forever. Jesus' earthly activity was limited, he was about to leave the disciples but the Holy Spirit would be with them, and us, forever. He dwells with us. He lives in us. Everything might be out of control, but you have a helper - the same helper that was there at creation and empowered Jesus' ministry. You have the Holy Spirit in you