The Torah in Parashat Vayechi tells of the special blessings which Yaakov granted to Yosef’s sons, Menashe and Efrayim, conferring upon them the status of individual tribes – “Efrayim and Menashe shall be for me like Reuven and Shimon” (48:5). Yaakov granted his grandsons these blessings when Yosef took them with him to see Yaakov upon hearing that Yaakov had taken ill. The Torah tells that when Yaakov heard that Yosef was arriving, “Yaakov strengthened himself and sat up on the bed” (48:2). It seems that he had been lying down, as he suffered pain and frailty, but made a special effort to sit up before Yosef entered the room. Rashi explains that Yaakov did this out of respect for Yosef, who was a powerful ruler and had the status of king, who deserved special honor.
However, Da’at Zekeinim explains differently, suggesting that Yaakov sat up in order to assure that his proclamation to Yosef would be taken seriously. If he had remained in a lying position when he proclaimed his special blessing upon Efrayim and Menashe, people might have disregarded it, thinking that Yaakov granted the blessing without his mental faculties fully intact. It might have been assumed that he had already lost his ability to think properly, and thus his proclamation was not binding. Yaakov therefore specifically sat upright to make it clear that despite his frail condition, he was fully aware of what he was doing, and he fully understood the significance and import of his proclamation when he granted this special blessing to his grandsons. (A similar explanation is offered by Chizkuni.)
Symbolically, this interpretation perhaps teaches us the importance of appearing and sounding sincere when offering compliments and praise. If we “bless” people in a lethargic, listless fashion, our words are not likely to be taken very seriously, and could easily be disregarded. When we extend a “blessing,” congratulating people for their good fortune or achievements, or offering compliments or good wishes, we should try to follow Yaakov’s example and “strengthen ourselves” to speak with energy and conviction. This will help ensure that our good wishes sound sincere and wholehearted, and genuinely express our true feelings towards the person in question.