Avodas Hashem means 'Service of G-D'

Stubbornness Just like a stubborn person does not give up on his set goals, one has to be very stubbornness in serving Hashem and strengthen himself in Judaism not allowing any obstacle to get in his way. Opposition Even the lowest and most flawed individual, who aspires to embrace fear of Hashem, adhere to all Mitzvot and avoid any transgressions, must endure numerous ascents and descents. Numerous times he will fall from his inspiration, spiritual feelings, confronting both physical and spiritual challenges and obstacles. Regardless, he must strengthen and renew his service of Hashem.[1] A person has to pass through many descents before he is able to permanently enter the Gates of Holiness and be able to properly and consistently keep the Torah.[2] Even all the Tzadikim and G-D fearing individuals had to pass many obstacles and tests before the reached the a level where they remained properly strengthened.[2] Descents Sometimes a person is purposely thrown down from his Avodas Hashem and loses his inspiration in Judaism, this was caused by Hashem so he will start again and awaken and strengthen himself with new energy to keep the Torah.[1]

[1] Eitzos Mevoaros- Hischazkus #31 [2] Eitzos Mevoaros- Hischazkus #32