I'd say one of the largest changes I've made in my life that have helped me move forward so fast is starting small.
Often, I will have a new amazing idea, get overwhelmed with the details, and never start anything. However, after reading many books and hearing it repeatedly, starting small is the key to starting something. I've realized how true that is; another way to put it for the perfectionist is "you can't perfect something that doesn't exist."
It sounds simple because it is. But hardly anyone does it, and I think that may be because of fear, fear of failing, or fear of losing something. In reality, you are just trying something new, and if it doesn't work, go back if you like.
Just taking that first small step was all I needed to do to start losing weight, not worrying about the details of what would come later, but just taking the first step and getting through that day was my whole goal. After that, I went through the next day, I didn't know how to do it exactly or the science behind the method I was using, so I trusted it enough to follow the plan and not deviate.
That's how I started my weight journey of losing almost 100lbs in about 7 months.
Key takeaways:
1) The key to starting something big is to start.
2) Don't look into the future; have faith, and do it for today
3) Nothing will change without you changing first