You needn't feel deprived of fun activities just because you're a parent. Try to schedule a fun activity that you can do with baby. Sign up for a baby class where you can meet other new mums. Take the baby in a carrier and go hiking, check out an art gallery, or hit the shops.
Get back into having fun without the baby. You can schedule a semi-regular or regular date nights with your partner. If you feel that you are unable to a babysitter just yet, leave the baby with a relative or a good friend. Perhaps there are other new parents who you can barter babysitting duties with. Every now and then, leave baby with dad for an evening out with friends. It’s a perfect opportunity for dad and baby to bond. If you’re breastfeeding, teach the baby to take a bottle. You’ll feel less constrained once you know that baby won't starve if you are away for a few hours.
Remember, it will get easier in time. Every month that passes, motherhood will become more manageable, and you will discover ways to work the pre-parenthood fun back into your life. And you just may find some new kinds of fun along the way.