weight problem

The doctor told Santa singh that if he ran 8 kilometers a day for
300 days, he would loose upto 60 kilos. At the end of 300 days, Santa singh
called the doctor over phone to report he had lost the weight, but he had a
problem.
"What's the problem?"asked the doctor.
"I'm 2400 kms from home and don't have money to go back and if i will run back my weight will be 10 kg.