In the days of the Beis HaMikdash the Children of Israel were by their very nature drawn by a genuine yearning towards the service of G-d; for them the demands of This World were a matter of necessity, to be dispensed with offhandedly, and without ardor.

In the time of exile the opposite is true: A man is drawn by nature to his bodily needs and to This-Worldly matters, while his divine service and his love of G-d are earned at the expense of considerable toil.