Lammens was making his World Cup debut when he spilled a shot from Pau Cubarsi into the path of Mikel Merino, who converted the rebound to give Spain an 88th-minute winner and send them on their way to the final.
The 24-year-old had come on as a second-half substitute for the injured Thibaut Courtois, winning only his third cap for Belgium in the process, but the moment ended in heartbreak.
"I spoke to him. He's obviously off on a break now, a much-needed break, I think a long World Cup," Heaton told the Manchester Evening News.
"It was obviously a challenging moment for him, but I think that's the life of a goalkeeper. As soon as you put the gloves on and go between the sticks, you have to be ready to deal with that. He certainly is. I actually think he'll be stronger for it.
"I think his personality is fantastic for a goalkeeper, so no issues there. It's obviously disappointing for him but, as I say, I do honestly think it can help him in the long run."
Lammens enjoyed an outstanding debut season at Old Trafford following his £18.2m move from Royal Antwerp, quickly establishing himself as United's first-choice goalkeeper and making only one major error all season, when a poor pass out led to a Liverpool goal, a mistake he was able to shrug off. Heaton, who won three caps for England during a long career of his own, says that experience leaves him well placed to help Lammens deal with the setback.
"I think you're trying to avoid it from preying on your mind," Heaton said. "Everyone's different, so everyone deals with it differently, but I think, from my point of view, goalkeeping is a position where something goes wrong, it's going to end in a goal, and goals can change games and cause you to lose, so you have to understand that and be sort of realistic with that.
"But I think it's certainly tough but his personality is suited for it. He's very strong mentally and he'll be absolutely fine. I've certainly seen that from him as a young goalkeeper coming into Manchester United and dealing with that unbelievably well.
"I highly doubt he'll be going into it with fear or worrying about what may happen; it's more about what you want to go and achieve, whilst also accepting if it happens, you can deal with it."