Arise, therefore, and, with the whole enthusiasm of your hearts, with all the eagerness of your souls, the full fervor of your will, and the concentrated efforts of your entire being, strive to attain the paradise of His presence, and endeavor to inhale the fragrance of the incorruptible Flower, to breathe the sweet savors of holiness, and to obtain a portion of this perfume of celestial glory. Whoso followeth this counsel will break his chains asunder, will taste the abandonment of enraptured love, will attain unto his heart's desire, and will surrender his soul into the hands of his Beloved. Bursting through his cage, he will, even as the bird of the spirit, wing his flight to his holy and everlasting nest.

Bahá’u’lláh, Gleanings from the Writings of Bahá’u’lláh, p. 320

From the billows of the ocean of Thy generosity the seas of eagerness and enthusiasm were revealed.

Bahá’u’lláh, Prayers and Meditations by Bahá’u’lláh, p. 246

Although in prison, I have experienced the utmost joy and fragrance, the heart was attracted, the spirit rejoiced, the eyes turned toward the Kingdom of God and the tongue mentioning the Name of the True One and displaying the utmost effort and endeavor in the promotion of the Word of God and the diffusion of the fragrances of God; yet, under all difficulties, there have been no shortcomings, nor hath there been any lack of enthusiasm. The call hath been raised uninterruptedly and the fragrances of holiness have been diffused through all regions and empires.

‘Abdu’l-Bahá, Tablets of ‘Abdu’l-Bahá v2, p. 344

Consequently, do thou show a steadfast and firm footing in this station, engage in guiding the people and call them unto the Kingdom; then wilt thou find how the divine magnet -- the power of the Word of God -- will attract the hearts and bestow ecstasy and enthusiasm upon souls! When thou reachest this station, there shall remain no obstacles and no veil shall intervene, and all that is thy highest wish shall be realized.

‘Abdu’l-Bahá, Tablets of ‘Abdu’l-Bahá v2, p. 358-359

Day and night, morn and eve, at sunrise and at sunset, we are remembering with all our hearts and souls, the friends of the Merciful One, asking God's help and confirmation that the believers of the pure territory, the Holy Land, may become excellent in all conditions of morality, characteristics, behaviour, manners, conduct and actions, that they may appear with ecstasy, enthusiasm, love, consciousness, assurance, steadfastness, firmness, concord and harmony, with bright faces and splendid beauty in the community of the world.

‘Abdu’l-Bahá, Bahá’í Scriptures, p. 359

It is easy to approach the Kingdom of Heaven, but hard to stand firm and staunch within it, for the tests are rigorous, and heavy to bear. But the English remain steadfast under all conditions, neither at the first sign of trouble do their footsteps slip. They are not changeable, playing fast and loose with some project and soon giving it up. They do not, for some trivial reason, fail in enthusiasm and zeal, their interest gone. No, in all they do, they are stable, rock-solid and staunch.

‘Abdu’l-Bahá, Selections from the Writings of ‘Abdu’l-Bahá, p. 274