Your short term goals will relate to your long term goal.
Continuing with our illustration of working part time you may decide that you must first complete certain projects you have already committed to. You will also need to be more selective about what assignments you can handle or need to ask for an assistant so you can focus on the main business and get help with minor tasks.
You may set a date to stop working overtime. You may set a date to ask for contract work instead of salary. You should plan activities that are spent with family and no work interruptions. Whatever your goals they should be clear steps to achieving your long term goal: spending more time with family.
These short term goals will help you measure your progress towards your long term goal. They will shape how you plan your time and clarify the VALUE of your time. Make your goals specific and give them a date to be completed.