I have read that the ability of a species to survive is dependent upon its ability to adapt. I think this is true. I think it is also true that our ability to succeed is in part dependent upon our ability to adapt.
The only constant is change. As things change, we need to be able to adapt.
We do this in very simple ways without even thinking about it. If the weather turns cold, we dress warmer. (Well, most of us do. I still do not understand flip-flops in the snow.)
Most of the time, though, adapting to change is not this easy. A new job, a new position, a new supervisor, a new owner, a new corporate culture all creates change and requires us to adapt to the new situation. We need to adapt to remain successful. The way we used to do things may not be acceptable anymore.
Frequently changes in our professional life are the result of changes in the economy and the world in general. We need to adapt to these changes.
We need to adapt in our personal lives as well. Changes occur. Our parents get older and require more assistance. Our children get older and require less assistance. Our lifestyles change and we need to adapt.
Change is often good and adapting can be fun. However, even when we do not want to adapt to a new situation, it is usually best if we do. The only other alternative is to leave the situation. We need to embrace the changes and adapt, rather than bemoaning the past.