This is the 5078th most frequent Portuguese word.
mentais
"Mentais" means "mental" in English, relating to the mind.
In this sentence, 'mentais' is used as an adjective describing 'desafios', showing that the challenges pertain to mental aspects.
Os desafios mentais exigem concentração e esforço.
Mental challenges require focus and effort.
Here, 'mentais' qualifies 'exercícios' as activities related to mental capabilities or cognition.
Os exercícios mentais ajudam a melhorar a memória.
Mental exercises help to improve memory.
In this instance, 'mentais' characterizes 'hábitos' as being associated with mental functions or states.