...and to start doing something that she loves instead of doing something that merely pays the bills.
This is a big piece right here. The better your inner motivation, the better your stamina will be. My brother has started and quit a thousand projects--a very depressing trend. But he's stuck with the last one and is near completing. He finally got to the point in his life where he needed to buckle down and get serious about trying to make a project pay off.
I'm no expert and a procrastinator myself, but here's some advice based on my observations.
Do not 'impulse buy' your project. There's the old adage about how if you see some cool new toy in a store you immediately want to buy,
don't. Instead, you should make yourself wait a month. After that cooling off period if it's still something you really want then okay, go buy it. Same with projects. Never jump willy-nilly at your first idea. Chew on it a while. Make sure you really want to, and that's it's an idea worthy of your time.
Do not have unrealistic expectations. For example, if you decide you want to try and learn 3D animation, do not expect your first, third, or twentieth attempt to rival Pixar in quality. It's better if you underestimate your abilities a little bit, especially when attempting something completely new to you. Grandiose visions and stonewall perfectionism are project killers.
Do not set unrealistic goals/deadlines. If you work 50 hours a week, do not try and finish a 150 hour project in a month. Anyone who's tried to complete NaNoWriMo will understand what a DAUNTING goal writing 60,000 words in a month is. Most people just
can't, and I know I'm one of them. Avoid putting yourself in a position that leads to project failure or disappointment.
Pace yourself. It's the tortoise that wins the race, especially when you have a job/life to keep up in the meantime. Have a schedule where you set aside a regular chunk of project time and stick to the pattern. This will mean sacrificing some of your free/social/fun time, but if you balance your work/fun ratio, it should be endurable.
Fan the flames of enthusiasm any way you can. Use mood music if it helps. Get people (like your cousin) to check up on you and periodically ask about your progress. Accountability can do wonders. Keep your eyes on the prize, because when you reach the goal line, the satisfaction you get from persevering is a tremendous reward.
Good luck!