Why do you think that is? Probably because words are your power! Words are also reflections of your thoughts and lead to other thoughts generated by the words you've just been using. And all of this leads to feelings. It is your FEELINGS that determine what you attract.
When people hear that their words are powerful, they think that just saying affirmations should bring them what they want. Affirmations do work but there are multiple aspects to this work. You have to carefully word your affirmation correctly. You have to make it believable (just like your goals) and most importantly you have to be able to accept it and divert your thoughts and feelings from the negative thoughts you're having. Those negative thoughts will derail the effectiveness of the affirmation.
When you've written the affirmation or even just a statement of your goal, it should be in present tense, not have any double meaning words (such as bills - that could mean the invoices you receive every month or the cash you carry in your wallet). There shouldn't be any trigger words for you either. I can't think of a specific example right now but I know that there are "positive" words that set some people off and will lead them down the wrong path toward a different momentum than they want.
Start by writing down the words that mean good things to you, that feel good and are words you want others to use to describe you or your life. For some people "epic" is a wonderful word. For me, for instance, I would never use it because I think it's overused and I don't like it. This is why you need your own list and your own words.
Once you've got the list of "good to use" words, list the things you want or look at your goal/purpose list. If you don't have such a list, then use contrast in your life to determine what you want. For example, I want a car. I have already listed the specifics that go with that car (color, type of transmission, type of car, how many doors, etc - see the post a few weeks ago). Start realizing that you have already achieved these things. Use present tense. Your subconscious mind does not know the future. You want to be telling the Universe that you want this now. Once you tell the Universe you want something, the Universe delivers it. "So why do I have to either use affirmations or continue to think I have it. I mean, it's not here yet so how do I know it's going to come." The last part of that sentence is key. It shows that you have doubt and are in the "lack" mode - you don't have this thing "yet" and you question whether it will come. This is part of the accepting and allowing. Then you let it go and it will show up unless you're concentrating on its lack. Letting go is so important. Once you feel the relief of letting go, you will see magic. I find this all the time when I'm sitting around hoping someone will call. Once I let go of that hoping (which is being needy), the phone rings. Sometimes I play with it just to see what happens. It never fails that as long as I really do let go and start thinking about something completely different, I get what it is I've been asking for. You will too. Remember, though, that there is the Law of Gestation and some things will not show up right this minute. But you cannot lose faith. You have to know that it will come but that you cannot regulate when it arrives any more than you can regulate how - that is called "outlining"- telling the Universe HOW you want it to come. I have talked about planning the rose and not digging it up every day wondering where the flower is. You know there is a specific gestation period for the rose and that it must follow it. Same goes for things you want. They will come when you have let go of the "need" to have it. Stop being latched on to the idea you have to have it. Just know that you've placed your order and it will arrive.
This is the difference between manifestation and materialization. Once you have asked the Universe for something, you have manifested it. The actual showing up is the materialization and you have to do your job of allowing/letting go in order for that to happen. The manifestation happens immediately. The materialization takes time. Use this phrase to help you let go - "Nothing and nobody can interfere with my peace of mind, prosperity, well-being, achievement of my goals, NOT even myself."
Read your words and use only the ones that make you feel good. Put them together in ways that make you feel good too. Be aware of phrases such as "you're killing me" or "it's killing me" or "I'm fed up" or "I'm sick and tired", etc. You could have some fun by listing the phrases you use and those you hear from others (especially kids and coworkers) and see what message they are giving your subconscious mind. Same with old sayings like "money doesn't grow on trees", etc.
Pay attention to your words and phrases. Be a wordsmith. You will rule your life even more than you do now by paying attention to the words that form your thoughts and regulate your feelings.