$20k?
Damn dude, all my friends getting married are spending a minimum of $50k. $15k gets you the venue for the night without anything else included or factored in (food, music, fucking chairs or tables or lights, etc)
Weddings are a predatory business.
Motivation is fleeting. Discipline is a trained skill.
Whatever thing you wish you had motivation for, make a schedule for yourself and start doing it. Pair it with something you like (“I run each morning and I get my morning coffee after I finish my run”) and stick to it.