I once dreamed of becoming a GM. :) But now I realize that it's not for me. The best that I can achieve is 2100+ and I think I'm on my way there.
As for your question, talent is a must for that level. But just as important is dedication and having the right and targeted training techniques.
Grandmasters know a lot:
- Openings and tons of theory
- Refined evaluation skills
- Efficient calculation technique
- Keen eye of combinations and tactics
- Patience (TONS of it)
- Determination to play for a win in almost EVERY game
- Throwing as many obstacles as they can when they're on the losing side
Now, there's no course that will teach you everything. The scope is just TOO WIDE. But you can start collecting instructive books that focus on different parts of chess mastery or, you can check out this course by GM Igor Smirnov:
Just to set your expectations, it will not make you a GM, and this course is not designed to be finished in a month.
What it does (and it's good at what it does) is give you a detailed and comprehensive training plan, which is what you are looking for. It's divided into 4 sections, and each section increases in difficulty.
Every section has tasks and training positions that are built from the ground up to target certain facets of your overall chess play. It starts with Thought Process Training, Attack, and development of Opening Repertoire. It builds from there.
While it will not magically transform you to GM level, his students who used the training plan / program have reported success.
I, for one, have gained 200 points from the first section, BUT not effortlessly. It took me like 3 months to finish the first section. It's a shame that my busy schedule is getting in the way and I haven't got back to the course for like half a year now.
But others, his private students, have gained more. Some have reached 2100, others less - there are a lot of factors to consider and it won't be the same for every student.
It gives you a detailed study and training plan that will take months or even years (in my case) to complete. I hope that helps.