The title promises a resolution, but the speaker's first move is to postpone. They put off dealing with their "hot body" until another day, and the reasons sound sensible: looking after it properly will take time, and the speaker wants to do it gently, like turning an old acquaintance into a friend rather than forcing anything. The plan is to go slowly and not "do anything suddenly."
Then the last lines undercut all that careful talk. Being out of shape, the speaker eats a cake or two. The joke is quiet and a little rueful, since the sense of the earlier lines is that the body deserves kindness, and the speaker's idea of kindness turns out to be dessert.
The mood is light, dry and self-aware. The short, plain lines sound like someone reasoning with themselves and half-knowing they are making excuses. It's easy to recognise: the gap between what we mean to do and what we actually do, treated with humour rather than guilt.