Why don't you try taking baby steps. For the first week just try to work on the project for like 10 mins a day. No more then 10 mins. Surely you can accomplish that no matter how tired you are. Then as you become more adept at what you're doing up it to 20 and then 30 mins, etc. I think you're becoming tired because you're overwhelmed. You're sitting there at minute 0 of the task at hand wondering how the hell are you going to get to minute 10,000. Well, you're not supposed to be thinking about the last step yet, you should be focused on the more immediate step and nothing else. As you gradually start to work through your project and see it coming together you will feel less and less overwhelmed and start to enjoy it.
Everybody knows you only live a day but it's brilliant anyway