Sorry, but that's not any excuses for you not to start learning! Looks like your problem is procrastination which we all struggle with. Old age is also not as bad we're lead to believe for learning. It's all about getting into the habit of studying. That can come after an idea that turns into a goal and is kept in motion by brute force will. Alternatively the peer pressure from school or a course can keep you going and meeting goals effortlessly.
There are now many easily accessible online resources like 3blue1brown's "essence of" series [1], Khan academy [2], or Brilliant.org's courses [3].
There are now many easily accessible online resources like 3blue1brown's "essence of" series [1], Khan academy [2], or Brilliant.org's courses [3].
[1] https://www.youtube.com/playlist?list=PLZHQObOWTQDMsr9K-rj53...
[2] https://www.khanacademy.org/math/calculus-1
[3] https://brilliant.org/calculus/