If I wanted you to calculate a bunch of derivatives for me, I could simply show you the algorithmic approach to the process and leave you to do it. With some practice, you’d get better and better at taking derivatives and could even become better than a mathematician.
The inevitability of long term goals is that you will face moments where it seems like the task you’ve set for yourself is too large, and that you’ll never accomplish what you want. These slumps happen all the time, and I’ve found that they usually occur – perhaps somewhat ironically – after a stretch of good progress. What once was novel and fun to work on now seems to be a lot of work for only marginal gains.