it's completely normal a tip is to use some natural lube but remember a little goes a long way. another suggestion is make sure you are in the moment if you are thinking of other things you may not have the mind set to get wet
Are you also having problems with lack of a sexual appetite. If the desire is there, then maybe your body doesn't naturally produce enough lubrication. That can be completely normal, it *****, but it's nothing wrong. You just need to make sure to add a lubricant. Just remember water based only with condoms. Although sometimes a hormonal change can cause this. I know someone who had a problem with producing lubrication after she started a specific kind of birth control.
If your sexual appetite is very low or just not there then maybe you have a naturally lower sex drive or maybe it could be a hormonal imbalance. From personal experience I know that depression can cause a low sex appetite, and hypothyroidism can cause that depression. If you feel that there is something abnormal or this is a new problem I suggest talking with a doctor. They will determine if you need blood tests done to test against a hormonal issue or if it's a natural problem.