There are two driveways I pass on my walks, and they tempt me.
The neighbours probably wouldn't mind if I strolled down them, long as they are; one leading to an uninhabited yard, the other to a yard where the owners aren't often home.
Still, I don't go. I'd ask permission first, and the owners would be put on the spot (what could they say but Yes, sure! Why not! even if they'd rather I didn't). So I walk on by.
You need to ask for what you want. Ask and ye shall receive; it's usually true. But people will often say yes or give you what you want when it's not really what they want, and, contrary to popular opinion, that's not their problem. It's mine, too; discomfort and/or resentment affect future relations, and I don't want to get my way at the expense of someone else.
The difficult part is being sensitive enough to be aware that asking for something, and the way we ask for it, and when, and where, may be putting someone on the spot, and figuring out how to ask (if at all) in such a way that the person can say no without losing face/ appearing unkind/ungenerous, etc.
It is difficult to say no.
"Will you look after my child?"
"Can I bring my dog to your house?"
"Will you speak at my wedding? Parent's funeral?"
"Would you help me with ... ?"
I'd like to think it gets easier, the more often you say it. But it doesn't, really. And we, the askers, would do well to consider that before we make our requests, and come up with ways of asking that leave the person with a respectable and even comfortable out.