Squeezing a Work Desk into My Windowless Guest Closet

I recently decided to convert my tiny, windowless guest closet into a makeshift home office since I desperately need a dedicated workspace. The closet is about 4 feet wide and 6 feet deep, with no natural light and just a single overhead bulb. I tried fitting a narrow desk and a small swivel chair, but it feels super cramped, and the lack of daylight is already messing with my energy by midday. I’ve added a few LED daylight bulbs and a small mirror to bounce light around, but it still feels like a cave. I want the space to feel as inviting as possible since I’ll be spending several hours there daily, but I’m worried about long-term productivity and comfort. Has anyone ever set up a workspace in a tiny, windowless room? What lighting tricks or decor ideas helped you avoid that cramped, gloomy vibe? Also, any recommendations on furniture that’s compact but doesn’t sacrifice comfort would be a lifesaver!