The mum-of-two posted an image of a single flower set against the background of a sunset, overlaid with a quote from Alison Aars which read: "When you finally learn that a person's behaviour has more to do with their own struggle than it ever did with you, you learn grace."
The glamorous star captioned it: "#be kind." Her fans rushed to show their support, posting loyal comments in response.
A couple agreed: "10 million per cent xxx," and: "This touched my heart xxx."
WATCH: Penny Lancaster shows off her stunning kitchen as she cooks mouth-watering meal
One wrote: "Sadly, I had to deal with a similar issue last year… I learned a lot about myself, and more importantly, other people."
A fourth chimed in: "Loving your positivity on MasterChef."
Penny shared an inspirational message to Instagram
The 50-year-old had to bounce back earlier in the week after her first episode of the cooking competition show aired.
Penny's initial attempt was received badly by judges Gregg Wallace and John Torode.
Asked to dish up some tasty calamari with homemade tartare sauce, the model made an error that caused her sauce to be inedible.
John said: "What I’ve got in here is a raw egg/oil milkshake. Unfortunately, I can’t eat that."
"You used whole eggs instead of egg yolks," Gregg explained.
The star is married to singer Rod Stewart
Lucky Penny turned it around for the second and third rounds, however, acing a pan-fried turbot with buttered spinach and a hollandaise sauce followed by a chicken and coconut curry inspired by a holiday to Seychelles.
She clearly turned around the judges' opinions of her cooking prowess, too, with Gregg calling the Loose Women panellist a "stand out cook".
Guest chef Mitch Tonks added: "The fish is cooked perfectly, it’s wonderfully seasoned, the flavour of the hollandaise is good, I haven’t got a fault with it, it’s really good."
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