You can help make sure your loved one doesn't get prematurely sidelined from daily life by preserving at least one activity that's meaningful to him or her. Look for ways for your loved one to continue contributing to a workplace or volunteer job, for example (perhaps by doing aspects of a job from home).
Don't let him or her give up a hobby right away when it becomes too complicated to pursue; instead look for ways to simplify the steps involved. For example:
Someone who loves to read can still read picture books to schoolchildren as a volunteer.
A gardener can take on potted gardens.
A diarist might like to dictate journal entries to a recorder (with help).
An office worker can stamp, stuff, or seal envelopes for a campaign or mass-mailing operation.
An avid cook can help with prep work, make a salad, stir, or otherwise assist or work with simple recipes.
Maintaining a sense of meaning and purpose is important in warding off depression. And even someone with noticeable memory loss has a lot to contribute!