Hi, I'm glad you feel better in your mood. I think severe depression does take a lot of energy out of you and we get used to not doing much.
Emijec is right, the way to find motivation and energy is to start doing things, small goals each day like the walking, getting out of the house, try a pastime you used to enjoy but in a low key way with no pressure.
Remember to praise yourself for the smallest achievement, even if you don't feel it.
Think of it like rehabilitation from a broken leg.
When the plaster comes off, you are weak and the muscles have wasted away. The only way to get strong again and walk well again is to use those muscles training them gently from small beginnings that you CAN manage slowly building up strength and stamina until you can do everything you need or want to do.
Your motivation is like a muscle and in the early days exercising it is very hard, but you can build yourself up and find your confidence again.

Best of luck.