What can I do to turn my study into a retreat for my quiet time?

How about a few potted plants and some candles? Pick a color or theme that relaxes you and slowly start collecting things that give you joy and place them in that room. "Shop" your house first, I bet you will find things you already have - pillows, a pretty throw, a comfy chair. And arrange or rearrange until you have a room that is soothing to you.

add some low lighting, a chaise lounge chair or big comfy recliner, candles, even some relaxing music.

Photos of your family and friends at happy times and places. Candles or scented oils are important . Smells and sounds are associated with memories . Perhaps even a small indoor fountain or Zen garden . Enjoy your retreat !

Simplify the room first. Take out as much as you can! Then, go for a calming color scheme - blues and greens are great for a quiet, peaceful feeling. Decide how much you want to put into this makeover - do you want to paint? Buy or re-do furniture? I strongly suggest that whatever level you decide to do for this makeover, make a plan and have a focus. Then whatever you do, it will all blend together, and be peaceful.

I totally agree by simplifying first! I also always feel like having books around makes me feel relaxed - think about what items in your home give you that homey feeling, and see how you can incorporate them into your study. Another thing that can help is warm lighting. Good luck!