Albert Barnes Commentary Psalms 102:3

"For my days consume away like smoke, And my bones are burned as a firebrand." — Psalms 102:3 (ASV)

For my days are consumed like smoke - Margin, “into smoke.” Literally, “in smoke.” That is, they vanish as smoke; they pass away and become nothing; they are spent in affliction and seem to accomplish nothing.

The idea is that in his affliction, he seemed to accomplish none of the ends of life. His life seemed to be wasted.

This is often the feeling in trial. Yet, in trial, a person may be more useful; they may do more to accomplish the real ends of life; they may do more to illustrate the power and excellence of religion than they ever did in days of prosperity.

And my bones are burned as an hearth - Or rather, as firewood or fuel. Literally, “They are burned as a burning.” The idea is that in his troubles, his very bones, the most solid and substantial part of himself, seemed to be consumed and to waste away. See the notes on Psalm 31:10.