The breathing in and out by counts thing frustrated me for a long time. It didn't help calm me at all, but the advice is everywhere.
I can easily shallow breathe into my chest all day long. That doesn't fix anxiety.
You need to breathe into your belly. Watch your belly rise and fall with each breath.
It works, but in my case it only works while I'm actively focusing on breathing, which isn't super helpful. As soon as I want to start thinking about the core problem again, my autonomic systems revert to the original problematic breathing pattern.
Instead, you have to address the core problem. The only long-term solutions seem to be:
1. Rationalizing away the core problem that's making you scared. If you're anxious that you're not achieving your goal, you can decide that's not a goal anymore.
2. Solving the problem.
Neither of these solutions are paint-by-numbers. Life is hard. Solving hard problems is hard. If you're a high motivation person and you set your goals to be aspirational, you may just have to live with the discomfort of anxiety.