Arduous
Part of speech: adjective
Definition: Needing or using up much energy; testing powers of endurance. Hard to climb.
Example sentence: I write because I admire the act of rationalization, of seeking clarity in one's understanding of the complexities of life, and I'm bad at it. I'm slow. Writing, which is an arduous and slow process, proceeds at the same rate as my sloth-like mind.
Hard
Part of speech: noun
Definition: A firm or paved beach or slope convenient for hauling vessels out of the water
Part of speech: adverb
Definition: With much force or effort.With difficulty.Compactly.
Part of speech: adjective
Definition: Resistant to pressure.Requiring a lot of effort to do or understandDemanding a lot of effort to endure., severe, harsh, unfriendly, brutal.Unquestionable.Of drink, strong.Having a comparatively larger or a ninety-degree angle.Of water, high in dissolved calcium compounds.Sexually aroused.Having muscles that are tightened as a result of intense, regular exercise.Of a ferromagnetic material, having the capability of being a permanent magnet by being a material with high magnetic coercivity (c.f. soft)
Example sentence: A soldier will fight long and hard for a bit of colored ribbon.