Dangers and threats, increased pressure and ticking clocks, miscellaneous challenges

Needing to bypass security to get inside a bank
Being incarcerated and wanting to escape
Having to dodge security cameras to secretly meet a lover at a hotel
Needing to hack into a computer system to obtain information
A white-hat hacker needing to get past a security system to identify its flaws
Breaking into a compound to kidnap or free someone
Illegally crossing a border to another country 
A hitman needing to get past a politician or celebrity's security detail
Avoiding security to break into a museum and steal an artifact
A character leaving their home without drawing the attention of police officers stationed outside
Military personnel having to evade enemies in hostile territory
Having to get something illegal past airport security
Students sneaking out of school without those in charge noticing
Having to guess a partner's passwords to investigate their online banking activity after money goes missing from shared accounts 
An underage patron getting into a bar or nightclub without getting caught

Creating a plan that has a lot of details
Securing schedules and blueprints
Trying to consider every possible contingency
Making sure they have enough time and privacy to get the work done
Having to secure questionable or difficult-to-obtain items without leaving a paper trail
Having to trust others for help
Having to create a cover story to tell parents, a spouse, or anyone else who isn't in on the plan
Hiring someone who turns out to be untrustworthy or inept
Something changing at the last minute, compromising the plan
The character being identified by someone when they're trying to fly under the radar
Setting off an alarm
Forgetting to take out a security camera before entering a room
Being stopped by authorities and having to lie convincingly