Recommendation for multivitamin. Me. ?

Hi i am 21 year old male. I have a poor diet and my weight is also bit high. I am 6 feet tall with 79 kg weight. I just do normal brisk walking for 30 mins in park n other full body stretches n some 15 pushups and 30 reps of 5kg dumble. I was looking for a multivitamin which i can take for temporarily basis n leave it once i start feeling well fitness wise n general health wise along with improve n healthy diet. So i searched net n found muscle tech multivitamin to be the best out there. So my question is can a normal person who doesn't do gym or active sports can take it on regularly basis. The bottle prescribes of 3 tablets a daily but since i am just talking it for general health. Can i take one tablet daily for 90 days as one pack got 90 tablets. Is it safe to consume above dosage for me.?