Quick answer
Living rightly oriented toward God tends toward long life, and wickedness tends to cut life short. The observed grain of how lives run, not an actuarial guarantee.
Read both lines
As an observation it is easy to defend: the life oriented by reverence tends away from what shortens lives, the rage, the excess, the schemes, and toward what lengthens them, peace, temperance, honest work, community. The wicked man's years are shortened from the other end: his own patterns are subtracting from his total. The register matters: the context strongly suggests tendency, not contract. Some who feared the LORD died young; some of the wicked die old and comfortable, and Psalm 73 nearly lost its faith watching them. The proverb tells you which way the current flows.
From this side of the cross
Your days are in kinder hands than a formula, and the length of your life was never the measure of God's love for it.
Related: Proverbs 9:10–11 · Psalm 73:3–17
New King James Version®, Copyright © 1982, Thomas Nelson. All rights reserved. Full copyright information. Scripture provided by API.Bible.
Go Deeper
If this verse has been used to put weight on you that it was never carrying, ask about it directly.