1) Arduousness 2) Laboriousness 3) Operoseness 4) Strenuousness 5) Toilsomeness 1) Difficultness 2) Difficulty 
In psychology effortfulness is the subjective experience of exertion in connection with an activity, but especially the mental aspects of an activity. In many applications, effortfulness is simply reported by a patient, client, or experimental subject. There has been some work establishing an association among reported effortfulness and objective ...
[n] - the quality of requiring deliberate effort
noun the quality of requiring deliberate effort