I am unfortunately not to aware of the connotations of the Russian idiom.
If it means "to overcome fear", I would suggest "to muster up courage" - (ri)trovare il coraggio di fare qualcosa, prendere il coraggio a due mani.
A sample sentence will help. I googled it to find some examples, but I am still not sure whether I am on the right track. Can it mean "to overcome resignation"?
No, держать себя в руках is not a correct translation for sure. May be собраться с духом is more correct...Anita, I beg to differ; IMHO собрать волю в кулак is a bit stronger than "pull yourself together", which I would translate as держaть себя в руках.