If you have a speech challenge, it is ideal to first seek professional help. If that isn't an option, never give up. If you want to be a motivational speaker, or if you just want your voice to be heard, never give up on the idea. Never say "I'm not good enough."
If you have health insurance, you may have coverage for a speech pathologist, if your primary doctor makes a referral. If you do not have coverage, and cannot afford a speech therapist, there are still many things that you can do on your own, or with a friend, that can improve your speech.
My voice box was damaged over 30 years ago, and I have been working with a speech therapist for the past 2 years. Working with a professional has made a great improvement in my speech. I am going to share with you some of my speech therapist's instruction, so that you may also benefit.
One of the things my speech therapist taught me was to breathe, slow down, and to speak at a consistent pace. When I get excited, or speak more quickly, the words often blend together.
"Diction" means how clearly every syllable of every word is spoken. A speech therapist can identify a list of your personal speech challenges. They can be consonants, syllables, words, phrases, and even sentences.
If you do not have a therapist to work with, you probably are already aware of some of your challenges to start your own list. Then, a friend who knows you well and is good at listening, can help you expand the list for your unique situation. When you first make your list, recite each line daily. After a while, the correct pronunciation that you are consciously practicing becomes subconsciously anchored. This is how you improve.
Projecting your voice is another aspect a speech therapist works on. Projection is related to the breath. If you are reading a sentence, you know ahead of time what the end of the sentence is going to be, and can measure your breath accordingly. If you are going to give a speech, practice reading it aloud many times each day, so that you can anticipate where the challenging phrases are going to be, and be prepared for them.
Both diction and projection may be easier when reading, as opposed to speaking spontaneously. A common error is to run the words together at the end of a sentence, trying to fit them in before taking the next breath. My therapist calls this "throwing up words."
Another thing to practice every day are tongue exercise. To make your tongue stronger, raise the tongue up to and press the top of your mouth for about a second. Do this ten times, three times a day.
You can also record yourself speaking and listen to your progress. If you are discouraged by listening to your voice, then I suggest that you listen to the recording with your therapist, or a friend, who can help you focus on how much you have improved.
In summary, there is no reason why a person who has a voice challenge cannot overcome it with the right help. A profession speech therapist is the best choice. Be sure to follow all the protocols your therapist identifies to practice your breath, diction, breath, pacing, and tongue strength.