Adulthood provides less developmental stages than youth, but each stage is vast in years and experiences. Each person will experience adulthood differently based on their choices, lifestyle, beliefs, genetics, and their customs. Remaining physically and mentally well remains a constant for all adults.

Early Adulthood (Ages 20-35)
Early adults are still often trying to find “their place” in the life. This is a time where most are trying to develop a career path or are beginning a new career. This can be a difficult stage for some, as becoming independent can present challenges and obstacles to overcome. This age is also a time where many begin to start their family, with the average age of new parents being around 26 years old.
Biophysical: For most, the body is generally finished growing, with the majority reaching adult height by the age of 21. While muscle and fat continues to grow with an average of about a 10-15 pound weight gain during this time, young adults generally find that their diet changes from that of a teenager, and falling out of shape can happen much quicker than experienced at an earlier age. Sleep habits begin to change, with about 1-2 less sleep required each night, and the brain’s frontal lobes have finally completed growing around age 25 – which generally helps with impulse control.
Psychological: Somewhere in this age group, typically the latter 20’s to early 30’s, the stress of figuring life out begins to decline. The pressure and responsibilities of work begin to normalize and while some have figured out the question to, “Is this what I’m meant to do for the rest of my life?” is answered. For others who may have started an independent life a bit later, this question may still remain.
Social: Relationships with friends and romantic relationships continue to be very important. Romantic relationships begin to take priority as the average age of marriage is between 27-29. Family also becomes increasingly important during the latter part of this stage. Keeping up with a social life and friendships sometimes suffer due to work, starting a family, romantic relationships, and financial stability challenges.
Spiritual: Young adults also begin contemplating their spirituality, especially as they begin having children. This is a time where decisions are made as to how children will be raised, perhaps identifying with a specific religion, what type of school the child will attend, and how important ones spirituality plays a role in life.
Middle Age
Middle adulthood provides a new set of challenges in life. By this stage, adults have landed a career and are striving to climb the ladder. There is generally more financial security, but for many, they find themselves part of the ‘sandwich generation’ during this time – meaning they are sandwiched between providing for the needs of their growing children and the needs of their elderly parents. Mentally and physically, this can be a testing time for some adults, as life can be challenging financially, and the stress of balancing work, family life, and social status can require much effort. 
The Golden Years
The golden years usually provide some of the best financial security, as adults are still working (hopefully in a well-established career at a high level job), have had years to build a savings and retirement account, and may be close to paying off big expenses such as mortgages. Children may be out of the house by this time, leaving adults in the golden years to experience the “empty nest”. During this stage, adults may even find themselves becoming grandparents during this phase.  However, for some, this stage can be challenging and mentally and physically stressful if life didn’t pan out as planned or hoped for.