The main reason I've experienced change in my life on the self-improvement track is the result of putting what I've learned over the years into practice. It can be very minimal at first. It doesn't have to be a great leap forward. If you were only to use one affirmation, for instance, but use it every day, you would notice a difference. The important thing is to stick to it. Make it a habit or daily action you would never think of not doing, like brushing your teeth.
When I used to deliver self-help courses, I always gave the participants a warning. This was that if they didn't act on what was covered on the course, then it would have been a complete waste of time for them. People would always nod their heads sagely, agreeing with me but I suspect it didn't really sink in for everyone.
Too often, though, people think that it has to be all or nothing. They don't do anything because they get overwhelmed with where to start or feel that they should immediately incorporate loads of changes into their life. I would say that it's better to do one thing, however slight. If you're learning to drive or swim, you wouldn't expect to learn it all in one go. Give it time. Start with just one action and build upon it. Many people who get interested in self-help do so entirely passively. They read the books, they go on the courses, take it all in but do nothing about applying what they've learned. That's such a waste.
Above all ,though, don't be hard on yourself if you feel these words apply to you. Just remember that it's never too late to start. I didn't really get going on this until I was in my 40s and even then it's been a long process. What got me started was the intial vision but what has maintained that vision is the daily application.