holding bitcoin a long time is good but you need more money to invest for long term invesment so you can get x2 or x3 of your money the more you invest the more money you will get.
Discipline is very important when you are investing for long term because it's a boring process and it takes time before you can see some profits, the price of bitcoin is very volatile while sometimes makes you tempt to sell and quit especially when there is a price fall that you don't expect will happen.
You have to eliminate that doubts in your mind, by trusting bitcoin you will always believe in its future and you will be at ease whatever the situation is.