Updated: Nov 24, 2021
Plant-based living has exploded in popularity recently, due to the negative impact of animal agriculture on the climate, the release of several eye-opening documentaries (Cowspiracy, Forks Over Knives, What The Health, The Game Changers, Hogwood and Seaspiracy), the host of vegan products available, the knowledge around animal products and their impact on our heath, and of course the zoonotic COVID-19 pandemic.
We all know now that what we eat affects not only our own health, but the health of the planet. And given the damage we've created, following a full or partial plant-based diet has never been so important. Let's look at more detail...
Animal agriculture is the leading cause of habitat destruction, species extinction, water pollution and ocean dead zones. [1-15]
A whopping 45% of the world's land is used for animal agriculture,  which accounts for more greenhouse gas emissions than the entire global transport industry.  These emissions are projected to increase 80% by 2050,  making switching to a vegan diet a crucial step towards fighting climate change. [19, 24]
With a global population of nearly 8 billion and growing, humans are already running out of space and resources, so keeping land for grazing, housing or growing (genetically modified) crops for livestock shouldn't be a priority. Only a fraction of the land currently used for animal agriculture would be needed to grow food for people, meaning less slaughtering, water usage (animal agriculture is responsible for 20-33% of the planet's fresh water consumption ) and pollution.
Over 40 years' research has shown that animal products aren't good for us. 
Humans are carbohydrate burning organisms (remember the Krebs cycle at school?). Our ancestors were predominantly gatherers not hunters.  And a diet based largely on whole plant foods is what's needed to keep us healthy. In order to thrive we need carbohydrate, fibre, protein and healthy fat (macronutrients), as well as vitamins and minerals (micronutrients). Almost all of which can be gained from plants. The only exception is vitamin D, which is made in response to sunlight (also found in lichen and mushroom) and B12 which is made by bacteria in the soil. Animal products are devoid of fibre, vitamin C and many micronutrients. They contain unhealthy saturated fat and cholesterol, toxins, antibiotics and hormones. All of these are detrimental to our health and over time lead to many common diseases such as cancer, heart disease, stroke, etc. 
Whole-food vegan diets are proven to reverse: 
Atherosclerotic vascular disease
Crohn’s and colitis
Inflammatory joint disease
If more people followed a plant-based diet it would end the suffering and torture of factory-farmed animals.
Over 70% of livestock in the UK are factory farmed  meaning they are kept in overcrowded, artificially lit, barns or cages. These horrific conditions, see Cowspiracy and Hogwood, create a breeding ground for animal and human disease (think our next pandemic). Quite often the ammonia from their sewage burns their lungs causing breathing difficulties. Their feet and legs rot from standing in their own faeces. They grow fat and sick from lack of sun and exercise, and often trample over the dead. This is the worst kind of life imaginable and has no place in civilised society.
To keep animals alive they are often given a cocktail of antibiotics leading, of course, to human antibiotic resistance. Hormones are routinely used to induce growth or continued lactation, etc. If you can stomach it - watch Dairy Is Scary and you will never, ever touch beef or dairy again. On second thoughts, please do - it will change your life for the better.
Would you consider going vegan? For your own health? The animals? The planet? Your kid(s) future? Hopefully for all the above. I hope you found this post useful.