In a past life, I studied hibernation in ground squirrels. I still find the process incredible: the squirrel literally drops its body temperature to ambient. Curled up in its burrow, it feels like a dead thing: cold, lifeless. Its heartbeat and breathing have slowed until they're nearly undetectable. Then Spring arrives, the squirrel warms up, and life begins again.
I think emerging from depression must be a bit like arousing from hibernation. You come partway out of your burrow, blinking sleepy eyes against the sun's glare. You look around, surprised: the world has gone on without you. The stark winter landscape is now burgeoning with new life: tender green shoots and leaves unfurling, blossoms shouting a riot of new color. Spring's heady perfume is overwhelming. Everything seems almost too alive.
Perhaps it's too much for you: you crawl back into the cold, dark safety of your own sadness. Or maybe you take a few tentative steps outside, welcoming the sun's rays on your pale skin. Don't rush yourself, it takes a while to get used to being alive again. Breathe in, breathe out. Feel the pounding of your heart. Stretch your cold muscles. Look for familiar landmarks, then venture forth.
Now you can start catching up on everything you've missed.