keep the pot boiling

boiling frog

A person who, or thing which, is in a gradually worsening situation without any realization of the peril until it is too late.

boiling hot

Extremely hot (having a high temperature: of an object, the weather, a living creature).

boiling mad

extremely angry; furious.

boiling point

The state of being heated, with high aggression.

cobbler, keep to your last

One should not criticise matters outside one's field of expertise; one should mind one's business.

earn one's keep

To perform satisfactory physical labor or to provide other worthy services in return for remuneration, lodging, or other benefits; to support oneself financially.

keep a civil tongue in one's head

To maintain a polite manner of speaking.

keep a close watch

to pay careful attention to a situation or a thing, so that you can deal with any changes or problems.