I think it is important to have a diversity of experiences, but experiences you can do well (so - not overcommitting and under delivering). I would not focus on the amount of activities you are involved in, but the quality as well as how you can show you've grown in that involvement. For example, I think colleges find it more revealing of someone's character if they volunteered at one place for three years and over time took on leadership roles, led projects, etc. versus someone who volunteered a little bit at many organizations but didn't show commitment to one cause or mission. Also, always tie back your experience to your future goals! All of those things are of equal value if you can share how they are helping excel your growth and future development. Hope this helps!