To live means to suffer, because the human nature is not perfect and neither is the world we live in. During our lifetimes, we inevitably have to endure physical suffering such as pain, sickness, injury, tiredness, old age, and eventually death; and we have to endure psychological suffering like sadness, fear, frustration, disappointment, and depression.
Although there are different degrees of suffering and there are also positive experiences in life that we perceive as the opposite of suffering, such as ease, comfort and happiness.
Life in its totality is imperfect and incomplete, because our world is subject to impermanence. This means we are never able to keep permanently what we strive for, and just as happy moments pass by; we ourselves and our loved ones will pass away one day, too.