Not everyone enjoys everything. Not everyone has the aptitude to do everything. That being said, there are (mental) exercises to try to relax, perhaps even have a glass or two of wine, and then there are actual physical exercises you can work through to ease you into anal play. Discuss your desire to please with your Master, work with him to get you to a comfortable point. Start with fingers, then a slim butt plug, etc. The hardest (bad pun) part of anal play is entry through the first spfinchter (did I spell that right?) - if you can allow him to ease in and then just hold it as your body adjusts, you will find your rectum will then actually welcome him in further. I happen to be a huge fan of anal play and can achieve multiple orgasms through this stimulation. I always encourage people to give new things a try (more than one) to ensure you don't miss out on some wonderful sensations. When all else fails, your Master will be so proud of you for your attempts to please him, and it can just be chalked up to a limit for you. Best of luck to you!