I don’t know if a besetting sin would be considered “a cross that we must bear” or even “a thorn in the flesh”, but even so the prayer below is instructive. To the degree that “our cross” involves dying to self and walking in obedience to God’s will and law, the last line is helpful – that the yoke would be easy and the burden light. O that that would be the reality when it comes to any area of besetting sin, that laying it aside would not be seen as a burden or hard thing to do.

From Valley of Vision..

The Grace of the Cross

Make it the ground of all my comfort
The livliness of all my duties
..the sum of all they gospel promises
The comfort of all my afflictions
The vigour of my love, thankfulness, graces,
The very essence of my religion
And by it give me that rest without rest, the rest of ceaseless praise.

O MY LORD AND SAVIOR,
Thou hast also appointed a cross for me
To take up and carry,
A cross before thou givest me a crown.
Thou has appointed it to be my portion,
But self-love hates it,
Carnal reason is unreconciled to it;
Without the grace of patience I cannot bear it,
Walk in it, profit by it.
O blessed cross, what mercies dost thou bring with thee
Thou art only esteemed hateful by my rebel will,
Heavy because I shirk thy load
Teach me gracious Lord and Savior
That with my cross thou sendest promised grace
So that I may bear it patiently,
That my cross is thy yoke which is easy, and thy burden which is light.