"Cross Yourself"?

Do what it takes to stay clear of sin
Self-examine your desires often
And cross yourself of them rather than
Fall prey to the lusts known of man

Alma 39:9 Now my son, 

I would that ye should repent 

and forsake your sins, 

and go no more after the lusts of your eyes,

 but cross yourself in all these things; 

for except ye do this

 ye can in nowise inherit the kingdom of God.

 Oh, remember, and take it upon you, 

and cross yourself in these things.