When in disgrace with fortune and men's eyes
I all alone beweep my outcast state,
And trouble deaf heaven with my bootless cries,
And look upon myself, and curse my fate,
Wishing me like to one more rich in hope,
Featured like him, like him with friends possessed,
Desiring this man's art, and that man's scope,
With what I most enjoy contented least;
Yet in these thoughts my self almost despising,
Haply I think on thee, and then my state,
Like to the lark at break of day arising
It is unspecified what he most enjoys, but evidently, in his despondency, things which ought to give him pleasure do not.  Note that in Shakespeare’s time “enjoy” also meant “possess”.  So the implication is that he no longer enjoys the love of his beloved, although that idea is countermanded by the final couplet. So the line is a paradox.
Sonnet 29