When people think about risk in relation to investments, they usually think about their money falling in value, this is only one risk. Another risk is opportunity cost, which is the risk of missing out on potential growth. Given the long-term nature of superannuation, this is an area where opportunity cost can really hurt us.
By far the biggest determinant in your investment performance is your exposure to growth and defensive assets. The more growth assets you invest in (shares and property), the higher the long-term returns. However, this also comes with higher volatility in the value of the investments. Conversely, more exposure to defensive assets will result in both lower volatility and lower returns.