Passage
If ye know these things, happy are ye if ye do them.
John 13:17 (KJV)
Nearby Context
John 13:15 For I have given you an example, that ye should do as I have done to you.
John 13:16 Verily, verily, I say unto you, The servant is not greater than his lord; neither he that is sent greater than he that sent him.
John 13:17 If ye know these things, happy are ye if ye do them.
John 13:18 I speak not of you all: I know whom I have chosen: but that the scripture may be fulfilled, He that eateth bread with me hath lifted up his heel against me.
John 13:19 Now I tell you before it come, that, when it is come to pass, ye may believe that I am he.
Study Lenses
The verse centers on "things" and "happy". It is saying that the verse draws attention to "things" and "happy", so its meaning should be read from those terms before moving to application.
The nearby context moves from verse 16's "Verily verily I say unto you The..." into verse 18's "I speak not of you all I...", so "things" and "happy" belong inside that flow. In John context, the local focus is the identity of Jesus, new birth, eternal life, and belief and unbelief.
A plain takeaway is to answer the verse's own emphasis on "things" and "happy" with trust shaped by these words, not by a vague optimism outside the passage.