The French idiom, ce n'est pas la mer a boire, translates roughly to "it is not the sea to drink", an expression meaning that a certain task or situation is not as burdensome and punishing as one may first percieve it to be. This may be a reference to the Nordic myth in which Thor, known as Þór, and Loki travel to Utgard, or Útgarð, the land of the giants, enemies of the gods. On the way there, they encounter a giant by the name of  Skrýmir, who travels with them and leads them to the fortress of the giants, held by the giant Útgarða-Loki and his men. The giant Skrýmir keeps stashes the food of the travelers in his own pack out of generosity, but then when Thor attempts to open the pack. After struggling with it, Thor gets so frustrated that he smashed Skrymir over the head with his hammer Mjollnir (typical Thor) , but the giant remains unscathed. Laden with fear and caution, the travellers avoid the giant for the remainder of the journey.

As they journeyed, the neared the giant's stronghold. Skrymir advised them to keep their pride to themselves, as Utgarda-Loki and his men would not tolerate it. Thor feels insulted at this demeaning comment, but Skrymir heads to the north without a farewell. The travellers walked east towards the stronghold, and eventually reached its gates, where they were able to slip through and enter the great hall. There lounged Utragda-Loki and his men, and Thor greeted him with courtesy. The giant lord claimed that only those who could prove their skill were worthy of staying in the stronghold. 

Loki proclaimed that no one could eat faster than he could. Logi the giant was his challenger in an eating contest, where they both ate their way through a trencher of meat and met in the middle, starting at either end. Loki ate all of his meat, but Logi ate the meat, the bones, as well as the trencher. Logi was declared the winner.

Thor proclaimed that no one could drink more than he could. In response to this, Utgarda-Loki gave him an enormous drinking horn, and said that even the weakest could drain it in three swallows. Thor gave three enormous gulps, and the level in the horn dropped, but it remained full. Thor returned the horn to Utgarda-Loki, who belittled him for his lack of might. In response, Thor accepted more challenges: lifting the giant lord's cat, which he could not manage, and wrestling the giant lord's old wet-nurse, who caught him off-guard and brought him to one knee.

The gods were teased for their failures, but were nevertheless allowed to stay in the hall for the night, and were treated with hospitality. When it was time for them to leave, Utgarda-Loki spoke with Thor outside of the hall in private.

The giant lord informed Thor that he had been tricked, and that his true might would have been the end of the giants, had they not avoided it. For the giant lord Utgarda-Loki was the same giant who had escorted them on their journey, Skrymir. The blows that Thor had attempted to land on Skrymir were narrowly dodged, and great chasms were left in the landscape where Thor had smashed it. The giant Logi who Loki had lost to was fire itself, and it consumed all that was put in front of it. The bottom of the horn that Thor had drunk from was connected to the sea, and Skrymir told them that when they returned to it, they would see how Thor's swallows had lowered it. The cat Thor attempted to lift was the Midgard serpent Jormangandr, and when Thor lost to the wet-nurse, he had been fighting old age herself. And everyone loses against old age in the end.

Thor attempted a final attack on the giant, but he disappeared before Mjollnir made contact. Thor was left gazing at the beautiful landscape.

So when you feel overwhelmed with your own struggles, remember that they could always be the work of mysterious and belittling giants, tricking you in order to conceal your true might.

Or they could just be smaller than they seem. Ce n'est pas le mer a boire.


Source: look here[link] for some interesting drawings of giants in thigh highs and Thor trying to lift a long-ass cat