You are probably right that these activities have become more difficult for him. It also is more difficult for a person with dementia to initiate an activity, even things they enjoy. Try to identify some areas of the activity that can be modified for him. Gardening is an activity that can be adapted. Raised garden beds or containers might help during the warmer months. At this time of year, indoor plants and herbs require less physical strength. Try doing an activity with him, which will help him to initiate, and give you a chance to gauge his responses. Ask for his help or advice with your own garden, or to sand some wood for a project of yours. He still has a lot of knowledge you can tap, and you still have time to enjoy his company.