My father's secret to financial success was to pay himself first. He would set aside a specific amount from each paycheck for long term investments. He then used the remaining amount for the household budget. The amount saved does not have be large if one is paying off bills or finances are tight
I have followed this plan since my teens. In the days of minimum wage jobs, I might have only paid myself 25 or 50 dollars a month, but with compound interest over time it really adds up.