Should means won't

One simple step in becoming more proactive is to use proactive language. Becoming more proactive is one of the best things you can do for yourself. If you want something changed, get up and change it. Don't expect others to do it for you. To do this, stop using language as a way to hide.

If you say "I have to do X", you are signalling that you have no influence in selecting the task. This is seldom true. The reason to choose this phrase is because it lets you of the hook. If you say "I choose to do X" instead, you are stating that X is the best thing you can do right now (otherwise you would do something else). But if you choose something, you can choose wrong. Choosing to do something makes you accountable to the outcome. Being proactive means to embrace this.

In a similar fashion, saying "I should do X" (or "I don't have time to do X") means to recognise that the task is important, but that you don't want to do it.
The first step to start doing it is to accept this. Everything we do (and don't do), we do (or don't do) for a reason. Instead of trying to convince yourself with force that the thing you don't want to do is important, accepting that there is an obstacle opens the door for investigation. Why do you not want to do this? Once you answered this question, it's easier to choose to do what you "should do".