Instinctive in the context of Fixed action pattern

Sexual intercourse (also coitus or copulation) is a sexual activity typically involving the insertion of the erect male penis inside the female vagina and followed by thrusting motions for sexual pleasure, reproduction, or both. This is also known as vaginal intercourse or vaginal sex. Sexual penetration is an instinctive form of sexual behaviour and psychology among humans. Other forms of penetrative sexual intercourse include anal sex (penetration of the anus by the penis), oral sex (penetration of the mouth by the penis or oral penetration of the female genitalia), fingering (sexual penetration by the fingers) and penetration by use of a dildo (especially a strap-on dildo), and vibrators. These activities involve physical intimacy between two or more people and are usually used among humans solely for physical or emotional pleasure. They can contribute to human bonding.

There are different views on what constitutes sexual intercourse or other sexual activity, which can impact views of sexual health. Although sexual intercourse, particularly the term coitus, generally denotes penile–vaginal penetration and the possibility of creating offspring, it also commonly denotes penetrative oral sex and penile–anal sex, especially the latter. It usually encompasses sexual penetration, while non-penetrative sex has been labeled outercourse, but non-penetrative sex may also be considered sexual intercourse. Sex, often a shorthand for sexual intercourse, can mean any form of sexual activity. Because people can be at risk of contracting sexually transmitted infections during these activities, safer sex practices are recommended by health professionals to reduce transmission risk.

Ambush predators or sit-and-wait predators are carnivorous animals that capture their prey via stealth, luring or by (typically instinctive) strategies utilizing an element of surprise. Unlike pursuit predators, who chase to capture prey using sheer speed or endurance, ambush predators avoid fatigue by staying in concealment, waiting patiently for the prey to get near, before launching a sudden overwhelming attack that quickly incapacitates and captures the prey.

The ambush is often opportunistic, and may be set by hiding in a burrow, by camouflage, by aggressive mimicry, or by the use of a trap (e.g. a web). The predator then uses a combination of senses to detect and assess the prey, and to time the strike. Nocturnal ambush predators such as cats and snakes have vertical slit pupils helping them to judge the distance to prey in dim light. Different ambush predators use a variety of means to capture their prey, from the long sticky tongues of chameleons to the expanding mouths of frogfishes.

Stretching is a form of physical exercise in which a specific muscle or tendon (or muscle group) is deliberately expanded and flexed in order to improve the muscle's felt elasticity and achieve comfortable muscle tone. The result is a feeling of increased muscle control, flexibility, and range of motion. Stretching is also used therapeutically to alleviate cramps and to improve function in daily activities by increasing range of motion.

In its most basic form, stretching is a natural and instinctive activity; it is performed by humans and many other animals. It can be accompanied by yawning. Stretching often occurs instinctively after waking from sleep, after long periods of inactivity, or after exiting confined spaces and areas. In addition to vertebrates (e.g. mammals and birds), spiders have also been found to exhibit stretching.

The will to live (German: der Wille zum Leben) is a concept developed by the German philosopher Arthur Schopenhauer, representing an irrational "blind incessant impulse without knowledge" that drives instinctive behaviors, causing an endless insatiable striving in human existence.

This is contrasted with the concept of the will to survive under life threatening conditions used in psychology since Schopenhauer's notion of the will to live is more broadly understood as the "animal[istic] force to endure, reproduce and flourish".