inured

flinty, leathery, resilient, stalwart

durable, enduring, everlasting, immortal, imperishable, lasting, permanent, stable, staunch (also stanch), staying, tenacious, unyielding

flourishing, prospering, thriving

able-bodied, brawny, muscular

fit, fortified, hale, healthy, husky, lusty, red-blooded, robust, sound, strapping, virile

annealed, seasoned, tempered

acclimated, acclimatized, adapted, adjusted

annealed, tempered

invigorated, vitalized

immunized

bolstered, boosted, braced, buttressed, enforced, forearmed, propped (up), reinforced (also reenforced), supported

broke in, limbered (up), trained

accustomed, conditioned, habituated, naturalized