It took Martin longer than the children to acclimate to the cold. (acclimate: acclimatize, adapt, adjust) A sedentary job had done little for his balance. (sedentary: seated, inactive, sitting-based) He had been warned that skills atrophy through disuse; he had never developed this one at all. (atrophy: waste away, wither, shrivel) His first abortive effort ended against the rail, one mitten missing. (abortive: unsuccessful, failed, fruitless; rail: railing, handrail, support bar)
A sportive teenager returned it. (sportive: playful, frolicsome, lighthearted) Each tried to conceal an insecurity. Martin felt too old and the boy felt too insecure to let his friends see him teach a novice. (insecure: uncertain, self-doubting, unconfident) Their ambivalence lasted until an elderly woman glided past backward. (ambivalence: mixed feelings, conflicting attitudes) Neither could hide his admiration.
The boy taught Martin to bend his knees. Martin helped the boy tighten his loose skate. At lunch their progress was modest, but warming up had done more to invigorate them than a cheering speech about overcoming adversity. (invigorate: energize, revitalize, refresh; adversity: hardship, misfortune, affliction)