cardio help

so i started running again.. second day runnin and i cant run for sht.. barely a mile.. used to run 3 miles in under 30mins before.. now no mo

what do i need to do to start off.. i completely forgot how to pace myself..

weight: 180lbs
height: 5.11"

also, could it be possible cuz i also changed my diet.. ?? tia

just go slow at first. u may not feel like ur making huge leaps and bounds and gains, but the key is to reinforce the habit of running. The more u get use to running itself, by default u'll be able to run for longer distances at a faster pace. Baby steps, even if u feel like ur just lagging ass, reinforce the habit of doing it. Cheers! and GL