This refers to their physical bodies decaying and dying. AT: "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. AT: "our spiritual beings are being strengthened day by day" (See: [[rc://en/ta/man/translate/figs-explicit]])
Paul speaks of his sufferings and the glory that God will give him as if they were objects that can be weighed. The glory far outweighs the suffering. (See: [[rc://en/ta/man/translate/figs-metaphor]])
The glory that Paul will experience is so heavy that no one can measure it. This can be stated in active form. AT: "that no one can measure" (See: [[rc://en/ta/man/translate/figs-metaphor]] and [[rc://en/ta/man/translate/figs-activepassive]])