I was 112 kg 5 years ago i'm 78 now but my thighs flaccid sort of, how to tighten my thighs !! did fast walking for couple hours help or i should run ?

Good job!: Hi. Good job on the weight loss! That shows commitment to a healthier lifestyle and perseverance. Walking (briskly) and jogging are both good. At 78 years old, comorbid conditions like heart disease, arthritis, etc need to be considered. But plenty of people your age run/jog, so if you're healthy enough for it, you pick. It needs to be something you like doing and will stay with. Good luck!