'Grievous' in the Bible

Just consider and meditate on Him who endured from sinners such bitter hostility against Himself [consider it all in comparison with your trials], so that you will not grow weary and lose heart.

For the time being no discipline brings joy, but seems sad and painful; yet to those who have been trained by it, afterwards it yields the peaceful fruit of righteousness [right standing with God and a lifestyle and attitude that seeks conformity to God’s will and purpose].

For the [true] love of God is this: that we habitually keep His commandments and remain focused on His precepts. And His commandments and His precepts are not difficult [to obey].