I find the best way of approaching a long task is to make a "to do" list, and then pick which one you fancy when you are in the right mood.
For some things, you need total dedication, for others you can do them in a hour or less.
Plus make a proper list of the bits needed for each thing on the list. It is very frustrating to start something, and then early on find that some small part is not to hand, or a bolt shears.
Preparation for tackling a long list is vital to avoid thinking, "stuff it, I just cannot be bothered". Small steps to climb a mountain, not giant leaps.
Alex in Norfolk, (currently about halfway through #3 restoration 3089R).