Self doubt seems to be the ongoing struggle for me. One thing is for certain, though, when you look at the people who succeed in reaching their goals, you will observe that they have found ways to mitigate or overcome that self doubt, even if on a daily basis. While there is a lot of advice out there regarding self doubt, I'm going to focus on two strategies that I've been using: the voice within and the voice without.
The voice within refers to self-talk. How do you talk to yourself? For a couple of years, I was a one-on-one instructor for young adults, and I was surprised how many of them talked down to themselves about themselves, even audibly. One guy would call himself stupid every time he made a mistake and would fret that he would never get it. I worked with him on changing his self-talk, suggesting he say things like, "I'll get it next time" and "I know I can do this!" His progress was slower than others, and that frustration frequently bubbled to the surface, but I kept reminding him that while his progress was slower than he wanted, he was still progressing! He was still moving forward and getting better! When you fail or fall down, how do you respond to yourself? This is extremely important. If you're trying to learn a new skill or a new subject, remind yourself that even the experts started where currently you are. Remind yourself that no matter whether or not you progress at the pace you would like to, you are still farther along the path than you were a month or a year ago. Adjust the voice within to be your biggest cheerleader.
The voice without refers to those around you. I have met so many people for whom there is no end to the obstacles they see and reasons why they can't do this or that. Take a look around you to the people you surround yourself with: do they see endless obstacles or limitless opportunities? I have found that one of the biggest factors for my success is who I listen to, so I have worked at finding the types of people who, when they face an obstacle, say, "how do I overcome that?" rather than the defeatist, "oh well, I guess I tried." The people who already engage in positive self-talk will be the first by your side when you fall down, saying, "get up! You've got this!" They won't let you wallow in self pity or give up on yourself. They'll be that voice for you when your own voice within struggles or fails. These are the people who, when you tell them about an obstacle you're facing, respond with encouragement that you can find a way around it, and they will often help you do just that.
While I can't say for certain which is the more important of the two voices, I do think the voices of those you surround yourself with are the more important when it comes to longevity. We tend to be influenced by those around us, so even if your struggle with being down on yourself, if you surround yourself with people who help you see the opportunities, who encourage you to keep at it, and who assist you with overcoming obstacles, you will soon find these encouragements repeated in your own mind, even when those people aren't around.
When you look at those around you, who are the ones that identify nothing but opportunities? Who are those that spot nothing but obstacles? Who are the ones that are your biggest encouragement when you have a goal? When you find something you'd like to learn, what does your own mind think? Do you observe only obstacles? Do you then answer each obstacle with an opportunity, or do you find your thoughts limiting yourself by these perceived limitations? Break free from the negative self-talk and try telling yourself that you can do whatever it is you've wanted to do, then start figuring out how to overcome that which has stood in your way and kept you from pursuing that goal or dream.