How can chanting a mantra help me handle anxiety before making major life decisions?

I am Tanya Malhotra. On the 23rd of June 1997 at about 7:00 PM, I was born in Jaipur. I have been quite restless for a long time. To be honest, I am baffled whether to avail the promotion at my work or to take a complete turnaround in my career. Every time I get into such a mood, it seems that my breathing is getting restricted, and my thoughts keep going over the same "what if" scenarios. One of my friends suggested that I should habituate to the recitation of "Om Shanti Om" or any other relaxing mantra daily before going out as a method of relaxing the mind when confronted with important decisions. It makes me ask myself if this would really be the clarity that I am seeking and if it is better to perform it in the morning, at night, or both. And then, how quick will the transformation be?