It is the perfect distance from the sun
Gravity
The earth has several factors that allow it to sustain life while its sister planets cannot. The most important of which is its location from the Sun. Earth lies within the "Goldilocks Zone" which is a distance from a star that allows for proper temperatures to maintain life. Deviation too far in either distance can make it too hot, or too cold, to sustain life.
It the earth was half its mass, then it might only be able to hold half the atmosphere. In this case, it may not be able to maintain many species of life as we know it.
Steam is a product of boiling water. Water boils at 212 degrees F. Steam rooms however are able to maintain a higher temperatures by adding energy and humidity.
Because it has sufficient gravity and a strong magnetosphere.
Birds and mammals are the only members of the animal kingdom which are endothermic, or "warm-blooded". This means they are able to maintain a constant body heat from within. Other creatures are ectothermic, or cold-blooded, meaning that their body temperature is influenced by external temperatures.
Well to maintain the oxygen in the earth atmosphere you need to make sure that the level of global warming is decreasing and less fumes will be able to make up the ozone layer. With a thinner layer around the earth this means that oxygen will be able to enter and exit the earths surface, allowing oxygen to still stay in the atmosphere.
To keep your blood sugar in the proper range you must make sure to eat right. By following a strict diet you will be able to make sure that you are keeping your blood sugar at the proper level.
The first organisms on Earth were likely simple single-celled prokaryotes, such as bacteria and archaea, that appeared around 3.5 billion years ago. These early organisms were anaerobic, meaning they did not require oxygen to survive. These primitive life forms eventually evolved into more complex organisms over millions of years.
They have no balls.
Time would be the least of your problems at the center of the earth. But if we could put a clock there that would be able to function at high temperatures and pressures, I don't think we would observe any time anomalies.
To maintain a proper skating technique, your foot needs to be locked snugly into the boot. If the laces are loose, not only will you not be able to skate properly, but you risk possible injury.