To die while still actively working or in the age or physical condition to do so (i.e., before retirement). The thought of growing old depresses me. I'd rather die with my boots on.
die with one's boots on
Also, die in harness. Expire while working, keep working to the end, as in He'll never retire-he'll die with his boots on, or She knows she'll never get promoted, but she wants to die in harness. Both phrases probably allude to soldiers who died on active duty. Until the early 1600s the noun boot denoted a piece of armor for the legs, which may have given rise to this usage; and Shakespeare used harness in the sense of armor when he wrote: "At least we'll die with harness on our back" ( Macbeth 5:5).
die with your boots on
If you say that someone died with their boots on, you mean that they died while they were still actively involved in their work. Unlike many businesspeople who die with their boots on, he has very sensibly left the entire running of the company to his son. Note: This expression was originally used to refer to a soldier who died in battle.
Die with your boots on was apparently first used in the late 19th century of the deaths of cowboys and others in the American West who were killed in gun battles or hanged.