Passage
In him was life; and the life was the light of men.
John 1:4 (KJV)
Nearby Context
John 1:2 The same was in the beginning with God.
John 1:3 All things were made by him; and without him was not any thing made that was made.
John 1:4 In him was life; and the life was the light of men.
John 1:5 And the light shineth in darkness; and the darkness comprehended it not.
John 1:6 There was a man sent from God, whose name was John.
Study Lenses
The verse centers on "light" and "life". It is saying that the verse draws attention to "light" and "life", so its meaning should be read from those terms before moving to application.
The nearby context moves from verse 3's "All things were made by him and..." into verse 5's "And the light shineth in darkness and...", so "light" and "life" 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 "light" and "life" with trust shaped by these words, not by a vague optimism outside the passage.