Ignition is usually the easiest of the three to check because on most engines, all you have to do is pull off a plug wire and check for spark when the engine is cranked. On coil-over-plug DIS systems, there are no plug wires so you have to remove a coil and use a plug wire or adapter to check for a spark.
Stress can affect every part of your body. muscle aches, head aches, how your hair grows, the texture of your skin, it can affect your menstrual cycle.
Celebrations and tragedies alike can cause a stress response in your body. All of your feelings, positive or negative, create physiological changes. Your skin, heart rate, digestion, joints, muscle energy levels, the hair on your head, and countless cells and systems you don't even know about change with every emotion.