Start out with a small percentage of your income and increase it gradually as you able. It is not as important to sock away $4000 dollars one day, but rather more important that you make saving and investing a regular habit.
How to Make a Million Dollars: To reach your goal of making a million dollars, you must stay laser focused

Being consistent has always helped me achieve my goals, no matter what they were. If you get into the habit of doing something only sometimes you’ll make no progress at all. Whenever I’ve failed at something it was because I’d not been focused enough.

I know this sounds like a load of personal development b*****ks, but it’s the truth. As my Dad would say - “You have to stick in if you want to do well”.