Vigorous, energetic, strenuous, lusty, nervous can all mean having or manifesting great vitality and force.
A person or thing is vigorous that has or manifests active strength or force and exhibits no signs of a depletion of the powers associated with freshness or robustness of body or mind.
A person or thing is energetic that displays abundant force or a capacity for great activity; the term does not necessarily connote the reserve vitality and force that vigorous implies and it sometimes even suggests an exertion of effort or a bustling activity that has little to do with inherent physical or mental strength; therefore the term may be used to suggest compliment or, less often, slight depreciation.
A person that is strenuous is continuously and zealously energetic, while a thing that is strenuous makes constant demands on one's vigor, energy, and zeal; in both cases the term implies no flagging of ardor or no avoidance of the arduous.
A person or thing is lusty that exhibits exuberant vigor or energy.
A thing (as a quality, a style, or an utterance) is nervous that conveys a feeling of continuing often forceful activity such as results from mental vigor and energy.