The goals you can complete same-day are manageable to attain. With just a few hours of work you can check something off your to-do list and get that sense of accomplishment. Long term goals aren't as forgiving.
When you want to achieve something that takes time like writing a novel, buying a house, or furthering your education, the first step seems almost futile. It takes incredible motivation to start, and even after you've begun the task can seem even more daunting than before. Questions arise such as, How can I sustain this for months? Even if I'm consistent, will I accomplish this in the time allotted or will it take twice as long?
Those questions can kill any momentum you've developed. Yes, some goals take time. Some take lots of time, but no matter how long it takes there must always be day one. If you become discouraged, put the long-term goal in the back of your mind, and accomplish what you can today. Even that long term goal requires something small be done before you go to sleep tonight. So do that thing, and allow yourself to feel accomplished. Let tomorrow worry about itself until you are ready to tackle it.