AM and PM are associated with 12-hour timekeeping, as opposed to the international 24-hour clock. The 12-hour system grew up mainly in Northern Europe, and spread globally from there via the British Empire.
The adjective STRENUOUS has 2 senses: 1. characterized by or performed with much energy or force. 2. taxing to the utmost; testing powers of endurance. Familiarity information: STRENUOUS used as an adjective is rare.
As the speech continues, Roosevelt claims that the strenuous life can benefit not just the individual, but also the entire country. He advocates imperialism as an extension of the strenuous life. America must become involved in global affairs, or else it will suffer as a nation.