The Sar Shalom of Belz zt'l explains that when a person moves to a new country, he generally doesn't move in a moment. He would wrap up his business activities, sell his property, say goodbye to friends, and make other arrangements. It takes time. But Yisro came immediately. He heard about kriyas Yam Suf, milchemes Amalek, and before matan Torah, which was only days or weeks afterward, he was already in the desert. Why did Yisro leave so abruptly?
The answer can be found in Rashi: "What did Yisro hear that caused him to come? He heard about kriyas Yam Suf and milchemes Amalek."
Yisro understood that the nature of Amalek is to act quickly, without thinking. Had Amalek taken some time to think things over, he would have realized that it was suicidal to battle the Jewish nation, for whom Hashem performed miracles, ten makos, and kriyas Yam Suf. Yisro understood from Amalek's spontaneous reaction that he must act immediately on his inspiration. He would never make the move if he would stall to think things over. He was inspired, so he had to act immediately.
The Yesod HaAvodah says that the attribute of zerizus is alluded to in the pasuk (Tehillim 111), טוב שכל, if you have a good thought, עשיהם לכל, bring it to action.
When Hashem offered the Torah to the Jewish nation, they replied, ונשמע נעשה. They didn't ask, "What is written in the Torah?" Instead, they jumped in and accepted the Torah. This is often the only way to succeed in avodas Hashem.
It states (Koheles 9:10) לעשות ידך תמצא אשר כל עשה בכחך, "Whatever you can do with your might, do it." The Baal Shem Tov zt'l says that בכחך means a good thought (because thoughts are called חכמה, which spells מה ח"כ). The pasuk is telling us בכחך לעשות ידך תמצא אשר כל, if you have a good thought, an idea that can bring forth a kiddush Hashem or kindness to others, עשה, do it right away. Don't procrastinate.
It states (20:23) מזבחי על במעלת תעלה ולא, "You shall not ascend with steps upon My mizbeach." Instead of stairs, there was a ramp. When walking up a ramp, one takes smaller steps compared to when one climbs stairs. The pasuk hints that spirituality is attained with small steps, always going higher and higher.
So, it could be that a person should begin with smaller steps, but he should start immediately. The good thought and inspiration that came to him is a gift from Hashem. If he fails to act upon it immediately, he can lose it.
