There are only two mistakes one can make along the road to truth: 1. Not going all the way. 2. Not starting.
The first one refers to not doing it seriously, we only do it to try whether it is for us.
Being guilty of not going all the way myself, I find the reason for this is we want an instant success.
Mostly at the beginning everything is promising and we are motivated, which I call honeymoon period.
When honeymoon period is over and we don't get the success quick enough, we try to find another new thing which we 'hope' will give that quick success.
The more we hop to new things, the more addicted we become to starting different things over and over to get that great starting feeling again and again.
The second one is, well, we can't overcome our fear, so with excuses we stay where we are.