Housing loan

The other day I went to my main bank to make an advanced repayment of my housing loan.
 This repayment was one tenth of the amount of my home mortgage.
I had better paid this as early as possible because the loan is equivalent to the principal and the amount of interest is equal to the amount of repayment. At the start of the loan, I had to pay one third of the cost for interest to my bank.
 If I didn’t make housing loan advanced repayments, I must continue the mortgage payment for 25 years.
 Sometimes I feel that 25 years is like a term in prison.
 Perhaps it could be worse.

Because I know of men who have borrowed the loan for 35 years when they were around 40 years old.
When will they work until?
Or will they use up all of their retirement money?
If they are fired, what will happen to them?
I feel afraid.So I plan to finish the loan in 10 years and plan to retire at around 50 years old in order to enjoy life.

Furthermore most Japanese houses might undergo major upgrades or reconstructions 30 years later .
 Even when you have finished the loan, you will need much money for them.
This two matters on home mortgages and the life span of houses are currently being discussed in Japan. 

I’m thinking about these things more than before.