Strap these over your shoes, walk up and down your lawn to spike and aerate it - simple!
They are like these:
https://www.ebay.co.uk/itm/405094772901?chn=ps&_ul=GB&mkevt=1&mkcid=28&goog...
Lawn aerator spike shoes (Trumpington Ward CB2)
This offer has been gifted to someone and is no longer available.