After writing my blog article What Are You Assuming? (see http://ping.fm/stats/oY5zY ) I found myself thinking more about assumptions people make. I ended that article with the advice to make assumptions your tool, not your prison. This time, let's look at one way people imprison themselves with assumptions.
If you hear yourself saying "he won't ..." or "they don't..." you are making an assumption against yourself. The best case is you catch yourself thinking this way and the thought is one more obstacle toward your goal. Anything else reduces the chance of getting what you want to zero because you stop yourself from asking. You may be saving the other guy time by doing so. More likely, you are denying him an opportunity as well as yourself.
Rather than assume against yourself, take some action to find out if what you want is possible. If you cannot take that action immediately, add it to your actions list. Be specific. WIll you research it on the Internet? Make a phone call? Ask someone at the next opportunity? Put it in writing. Forgetting to take action is as effective a block as assuming against yourself.
Asking someone for something is a skill. One book I like on this subject is The Aladdin Factor by Jackk Canfield and Mark Victor Hansen. They would tell you to ask as though what you want is reasonable and with the expectation of getting what you want. The book offers much more help on developing this skill.
Don't assume against yourself. Be confident in asking for what you want. If you aren't, who will be?