Both regular and irregular involvement in sports leisure can result in heightened SWB. Serious, or systematic involvement in certain leisure activities, such as taekwondo, correlates with personal growth and a sense of happiness. Additionally, more irregular (e.g. seasonal) sports activities, such as skiing, are also correlated with high SWB. Furthermore, the relationship between pleasure and skiing is thought to be caused in part by a sense of flow and involvement with the activity. Leisure activities, such as meeting with friends, participating in sports, and going on vacation trips, positively correlate with life satisfaction. It may also be true that going on a vacation makes our lives seem better, but does not necessarily make us happier in the long term. Research regarding vacationing or taking a holiday trip is mixed. Although the reported effects are mostly small, some evidence points to higher levels of SWB, or happiness, after taking a holiday.