It’s no secret that while you’re writing you’ll experience stops and unforseen events, and this will make you age ten years in a second… but it all depends on how you will react to it and what you’ll lear from it, this is what will make a difference.
You won’t learn only stuff about your topic (even though what I’ve learned this way will be useful, of course), but you’ll learn tons of stuff about yourself, if you’re aware enough to acknowledge it.

To sum up I could say “Calm seas don’t make sailors”, but to go a bit more into details I’ll, guess what, list things for you 😛 here’s what I feel I’ve learned… and I’m far more happy about this than about what the thesis is worth on its own

1) beginning and forcing yourself to go on is really the hardest part, but you’ll eventually get used to it
2) giving yourself little goals is soooo useful, this way you won’t be overwhelmed by the “ohmygawdI’llneverdoallthiswork” issue
3) then give yourself small rewards (read 100 pages? eat a cupcake. wrote 10 pages? paint your toenails. fixed two chapters? have a nap. etc)
4) sometimes stating (asserting 😉 ) things is better than to ask for: if you say something as it is already a matter of fact, it’s likely to be taken with no opposition or objection
5) listening to some soft, low volume, classical music really helps to be more productive… like cows with mozart!
6) force yourself every single day to do at least a little work, no matter how little it is, no matter if you’d rather go to the dentist and have him rip off your wisdom tooth (or all four of them, in one session)… this way, the day you’ll want to work (or won’t mind to) you’ll find yourself with tons of work already done
7) have some time for yourself, otherwise you’re going to burn out soon
8) “being tidy and organized” doesn’t have the same meaning for everybody. To one migh mean to have nothing out of place, to another one something different. When you’ll have found your own mental and practical organization and tidyness you’ll be set!
9) “In ten years, will this still be so important?” this is one of the best questions ever! ask it yourself when you’re upset for something… (I could scale down the “importance” of an issue to less than a month, then to a week… and it’s already gone XD)
10) sadly in life you’ll have to deal with real morons and negative people (someone doesn’t need to be pessimist, or evil to be negative… to me negative people is those frustrated people that need to shower you with their frustration, but hello? it’s not my problem… those people that leave you kinda tired after seeing them… those people you’re not thrilled to see if it happens to meet them or if you know you have to) even more sadly there’s nothing to do against this kind of self righteous stupidity… so just deal with them as fast as you can, don’t argue and change path as soon as you can 😉
11) with these kind of people, also, sometimes asking “please” and saying “thank you” is seen as a sign of weekness… as soon as you realize it change behavior and remember point 4!

then, for stuff I’ve learned strictly about myself (stuff that may not appeal to a general bulletpoint :P) here the list goes on:
12) I had the pleasant surprise to find myself strong enough to get angry and “fight” for those battles I thought it was worth to fight (instead of getting all nervous and teary)
13) I realized that when I AM happy of what I did (how I did it, what I achieved etc) it really does NOT matter what others think (actually I was thinking “and screw the rest”… oh I’m so ladylike when I talk like that…)
14) I liked myself more for being able to find so many positive things in a rough period ^_^