Covalent electron bonding is very similar to marriage. Two or more people who are married, share everything, just like covalent bonds share their electrons with one another.
This husband and wife, share the bathroom. The wife brushes her teeth while the husband uses the toilet.
This is very similar to how covalent bonds stabilize themselves by sharing their electrons with one another, allowing for a bond to form which links them together
This couple's goal is to both finish dinner full and satisfied. In the same retrospect, the goal of all elements in a covalent bond is to achieve an octet state, where each element has 8 electrons total, while sharing all of them.
This couple will share their dinner together, just like how O2 will share its 12 valence electrons total in a linear double bond.