Individuals' overall health and quality of life during COVID-19 pandemic were impacted, especially the level of physical activity(PA). Social distancing healthy and confinement procedure took part in individual`s lifestyle and their daily routine, hence, their health. This study aimed to investigate (PA) level of the Saudi adults during COVID-19 pandemic confinement that have an impact on their mental health. Furthermore, this study is exploring changes in the lifestyle behaviors, health and mental health attributed to the gender variable. A self-reported across-sectional questionnaire was spread online on a sample of (280) Saudi adults(n:160, 57.1%: females, n:120, 42.9%: males). Some variables were collected: The demographic data(through) a self-completed DCI, mental health was assessed by WHO-5, the (PA) level ( by using IPAQ), and body mass index (BMI) (based 0n self-reported weight (kg) and height(cm). Statistical analysis: means, frequencies and percentages were used to present results. Also, Chi-Square test for categorical variables, and one –way ANOVA test was used to compare between the groups. Likewise, Pearson correlation analysis was used to examine the relationships between (PA) and mental health. The results of this study revealed that individuals at the high level of (PA) (16.4 ± 3.8) recorded higher results in the state of mind index than people did of the average level of PA (14.2 ± 5.0) (p<0.0001) as well as higher than people with low PA (122) 5.5 ± 4.7) where the differences were also morally significant (P<0.0001). Males showed a higher level of PA than females. This study concluded that during COVID-19 quarantine, factors such as (PA) and sleeping patterns were allied with steady and healthy state of mind among Saudi adults. One  of the recommendation of the study is to encourage Saudi adults to engage in PA by using appropriate media tools to spread the instruction of these practices using.