Can the particular activity be done later? Defer it! Can it be done by someone else? Delegate it! Does it need to be done at all? If not, consider deleting it!
Commitment is something that comes from understanding that everything has its price and then having the willingness to pay that price.
One of the main areas that I work on with my clients is shedding these non-supportive beliefs and replacing them with beliefs that will help them.