What Causes Weakness In Neck Muscles?

Hi, Dr. I am about 28 yrs old and my daily work routing is that i get up early in the morning 7:00 AM and go for my job and travel about 80 KM per day on Motorbike and it take about 2 hrs of travelling daily. 40Km/hr. and In the evening i regularly sit on computer for about 2 to 3 hrs for work at late night some times 10 PM to 1 AM.
NO exercise but 1 km daily walk.
Whenever i got up my head and neck muscles get stuck and i feel uncomfort, after half hr then will relax but whole day i feel muscles strength in my head and neck. and my whole body reacts lazyness. please provide me, solution for this what should i do.
Thanks.