Taking photos in your garden or in nature can be very relaxing. That is if you are just there to observe and capture with your camera. Try and give yourself enough time. You must not be under pressure to produce something special.
Creative Mind
What you do is ... look around and try and find something that you can take a photograph of. Don't be too picky. Do not try too hard. You just need to get into a creative mindset.
Go Digital!
I have to add that I have a digital camera in mind. It is just far more difficult to relax and take photos, if it is costing you more with every click of the camera!