Yes. Have children who will take care of you when you grow old. One way you did it was that when you started to get too old to actively work your land you left the holdings to your son (or daughter and her husband) with the provision that you could stay and be cared for. E.g. by having a cottage constructed on the lands close to the farmbuildings. It wasn't uncommon for several generations to share a house either.

Older generations would participate in the work on a farm to the extent of their ability. E.g. looking after children. Yes, grandma babysitting you has ancient roots.

This remains to be the case in many societies that are still primarily agrarian. It was also how most countries that today have organised elderly care up to the 1800s worked. In the 1800s Sweden (what I know best) the municipalities are gradually given responsibilities that used to belong to the parish, like care for the poor, infirm and elderly. All of these could be housed in the local parish "poorhouse". if there was no family able to or occasionally unwilling to care for their own.

If you were wealthy enough, and lived close to or in an urban centre (usually) there existed hospices where you could bequeath wealth and you would get care and room and board. A retirement home of sorts. Though it cared also for sick and poor. These were normally run by charitable institutions and unsurprisingly the church or holy orders. E.g. in Stockholm the parliament house is today located on Helgeandsholmen. This island is so named because in mediaeval Stockholm it contained the Helgeandshus, the House of the Holy Spirit, where a charitable institution ran a hospice for care of sick, poor and elderly. This was supported by the burghers of Stockholm and other generous donors. And you could "buy" a spot to live there.

This is very much the exception though as there were never enough space to care for all elderly (fewer though in number then than now), also the reason you were expected to pay for your spot if you could. More likely was that you ended up in the care of your immediate family. So make sure your son marries nice girl and make friends with her. Because you'll be relying on her kindness before too soon.