Not all change is hard. If I decide to change my shirt, the change can happen immediately - just find a shirt I like, pay some money, and put it on.
But sometimes change is hard. If I decide to get in shape, that decision alone won't change me. I need to consistently do the right things over an extended period of time before the change sticks - which means that I need to make a lot of right decisions everyday for a long time.
So when change requires that we consistently do the right thing for a long period of time, then it becomes hard - especially if it entails overcoming old habits.
Help them make right decisions
Change in your Organization is no different - some changes will be easy because they are instant (e.g. changing a logo or moving offices) and other changes will be hard because they require consistent actions to be taken over time.
If you are implementing Salesforce, that is a change that requires people to adopt new actions and form new habits - so your implementation plan needs to take that into consideration.
You can't simply tell your organization "Here's a new shirt - put it on" and expect to be done with it. You have to help everybody make the right decisions every day for a long time until the new actions become old habits.