It seems like you will spend most of your time learning. So if you can increase learning speed, you will be able to learn about more topics and go deeper in fewer topics than you usually would. Yes, this is one additional thing to focus on, but if you do this early, you will cut other's time cost by significant factor.
Also it will make your decision making process, as there are few (actually a lot) bugs in human decision making process.
First thing to do is to learn at least a bit about cognitive sciences (how brain works).
For example http://en.wikipedia.org/wiki/Thinking,_Fast_and_Slow is good starting book.
Meditation is good, but it is even better if you meditate and know a thing or two about brain. My personal view of meditation is that it has similar effect to learning a bit about cognitive science. If you know/do both benefit is greater.
If you are usually unable to focus, your mind wanders a lot, try zen meditation. If you already have ability to focus try Vipassana meditation.
After that, you can focus on your aforementioned topics. Try each for week or two.
Once you start doing something, you will quite fast know if you want to continue or not.
(meditation helps here tremendously)
You have plenty of weeks left in your life, if you spend 25 weeks learning a bit about stuff, even if you decide that none of topics interest you, you only spent half of year, and you have learned something. It is not wasted time. IMHO way too many people waste so much time on facebook, tv or similar things. You should take your time to rest and have fun, but until we have utopia it can't be 24/7.
PS. If even after all this you still want to go deep into many topics and you are aware that it is not feasible, throw dice/coin. Coin flipping is easy.
Make list of topics, throw coin for each topic in list. Tails means that item is removed.
Repeat until you are left with amount of topics that you think you can handle.