Megilas Rus - Rav Itzele Volozhin - Naomi Kept Her Eye On Rus's Every Step
Rav Chaim Kanievsky was once asked how can we be Meilitz Yosher on the us Jews when our enemies show a great willingness to blow themselves up for their beliefs while we do not display such bravery? He answered that they are being driven to suicide by the very powerful Yetzer Hara, whereas our mesiras nefesh is being obstructed by him.
These same sentiments are echoed by Rav Itzele Volozhiner in Megilas Rus (1:18). After Rus tells Naomi that she will follow her back to Eretz Yisroel, "VaTeireh Ki Misametzes Hi Lalaches Ita", she saw that Rus was strengthening herself to go with her so she stopped trying to talk her out of it. What did Naomi see?
Rav Itzele says that in the struggle within every man between spirituality and materialism, the supremacy of one comes at the expense of the other. Therefore Jews are generally physically weaker than their gentile counterparts. "Torah Mateshes Kochoi Shel Adam", the torah drains the energy out of person. To read Divrei Torah when you are tired is very difficult, but to read a book is much easier. Learning Torah and doing Mitzvos is physically exhausting task because the pressure has an adverse effect on the body as the gemara says in Shabbos (86b).
Naomi did not want Rus to come with her for the wrong reasons. She knew that their life would not be easy in Eretz Yisroel. She kept warning Rus of the difficult life she would face. When Naomi saw "Ki Misametzes Hi Lalaches", that Rus was "shlepping along" and not skipping with a spring in her step, full of optimism and a twinkle in her eye about the potential good life she would have, she realized that Rus was going for all the right reasons. She was fighting her Yetzer Hara in order to continue. Nomia then relented and took Rus along.
When your mission is in doubt, a clear road can often be the sign of the Yetzer Hara hard at work helping you along in the wrong direction. But when you know you are on the right path, don't let the obstacles scare you. It is just the Yetzer Hara up to his old tricks. If you want you will overcome him.