Well it depends. For some women its easy and some its not. You have to have a clear mind and the right emotion.
Now when your mind is elsewhere and your stressing, of course you wont get one. I notice that too. So what you need to do is really be in the mood and be focused. Dont think too much, go with the flow and be into it. You have to want it for it to come. Its the way you will expierence it best. Sometimes for women, being on top is the best, have him be still and do your own rythym until you can feel it coming. And then let him try his way. Its the way to satisfy each other. Try different positions not old ones. Sometimes lying on the floor you can feel it or on the bed and lean up a little bit, meaning lift up your bottom a bit for him to reach your soft spots. But remember let your mind go, no stress, no worries, no thoughts at all. Just be into it. Work with your husband on it.