Does groaning about Ramadan, fasting, and prayer—and saying, "Oh, how long Ramadan is; I wish it would end so we could rest a little"—invalidate the reward, or is it sufficient to abandon these whispers?

Performing acts of worship with a good heart and a cheerful disposition ensures a complete reward, whereas annoyance diminishes the reward to the extent of one's displeasure. For this reason, scholars have considered part of the meaning of ihtisab (seeking reward from Allah) to be performing fasting and qiyam (night prayers) without finding them burdensome or grumbling. As for waswas (whispers/obsessive thoughts), they do not harm the servant if he performs the act of worship with a good heart, and he must strive against them and repel them. This enjoyment of obedience is only attained through mujahada (struggle and striving). When the mujahada is sincere, Allah will grant the servant success in fulfilling the truth with ease and willingness.