One of the first signs is your succulent leaning toward the window. Rotating it helps the look, but it doesn't fix the lighting.
A lot of succulents get their color from light and stress. Without enough light, many fade and revert back to a plain light green.
Without enough light the stem grows taller between the leaves. You get gaps, a weaker stem, and a plant that's more prone to rot.
A stretched succulent won't shrink back. Cut the top off, let it callous over, then replant it. The base will push out new offshoots too.