When you need to do something, and you start feeling that initial resistance, program yourself to break the task at hand into smaller pieces immediately and just get yourself to do the first one in the sequence.
For example — Going to the gym — becomes:
In most cases, finishing the first task will trigger a momentum, and that will make it easier to complete the remaining mini-tasks, and by default the primary activity you started with — which in this case is a successful gym session.
And it all started with placing some gear in the bag.
Now, just take any task you tend to procrastinate on the most and apply this simple hack ;)