Imagine how much influence you could gain over people by connecting to their emotions. All while helping them through THEIR difficulties and troubles. This is rarely taught in career development courses seemingly because it is so basic. But it is highly effective and you should use it.
Learn how to direct your audience's attention to associated concepts that will make it more likely to for them to say yes to your future request. This easy concept and ways to deploy it to gain influence over people are explained here.
Visualize your past successes before you make a presentation or do an interview. Persuade yourself to a killer performance.
If your persuasion skills are not as good as you hoped they should be and you are not getting what you want in life, it is really not your fault and I understand your frustration. I was once in your position. You have been misled and mostly taught the wrong ways to persuade by the confusing advice out there.
You would never think to get someone to change by actually joining in their behavior. But this is one of the best ways to get change that you've never been taught. The best persuaders use it and you should too.