"If any man serve Me, let him follow Me." Speaking of death, and requiring the following which is by works. For certainly he that serveth must follow him who is served. And observe at what time He said these things to them; not when they were persecuted, but when they were confident; when they thought they were in safety on account of the honor and attention of the many, when they might rouse themselves and hear, "Let him take up his cross, and follow Me" (Matt. xvi. 24); that is, "Be ever prepared against dangers, against death, against your departure hence." Then after He had spoken what was hard to bear, He putteth also the prize. And of what kind was this? The following Him, and being where He is; showing that Resurrection shall succeed death.
Source: Homily on the Gospel of John 67