This refers to their physical bodies decaying and dying. Alternate translation: "our physical bodies are getting weak and dying" (See: [[rc://en/ta/man/translate/figs-explicit]])
This refers to their inward, spiritual lives getting stronger. Alternate translation: "our spiritual beings are being strengthened day by day" (See: [[rc://en/ta/man/translate/figs-explicit]])
This can be stated in active form. Alternate translation: "God is renewing our inward being more each day" (See: [[rc://en/ta/man/translate/figs-activepassive]])