In your work environment, the things that are constantly present are schedules and deadlines. Most activities that you do, have some form of time limit attached to them. This limitation of time acts as a strong external motivator and for many tasks, we become dependent on them to achieve objectives.
While on your sabbatical, you will have neither a deadline nor a schedule. Either of these, if present, will be self-imposed (and hence flexible). So, basically, your external motivators are gone.
Whats left? You.
The most important thing to do is to look inwards. The only thing that will make you get up, sit on your desk and do something productive will be intrinsic motivators. So, any tasks that you perform will have to leverage this renewable resource.
Intrinsic motivation comes into play when we perform tasks that we enjoy, tasks that we do not consider work, but play. Remember how immersive a game feels? Remember the state of flow that you were in? That mental state is what you really need in your sabbatical.
No really, how?
Think about yourself and you aims in life. Think about activities that get you in a state of flow. If you have a smartphone, download and use a ESM application for a normal work week. This will remove any internal biases that you have and will give you a real idea of what tasks get you in a state of flow.
Once identified, (you may or may not like the list) try to figure out projects or tasks that you can do related to these activities. Make a list of these.
Now, prioritize them according to what you feel is most important or will help you most in furthering your aims.
Finally, create rough deadlines for each of these activities and if you so wish, create a schedule, as well. I recommend that you dont, but thats up to you. You will realise that when you do the tasks that you enjoy, you wont need a strict schedule or strict deadlines. Work will move along on its own.
You will spend the next five weeks playing through work this way! Enjoy your sabbatical.