A good warm-up raises body temperature, rehearses the movement you are about to load, and wakes up the nervous system. It is not the same as a full mobility workout—save long static stretching for after training or separate sessions if you enjoy it.
Start general (five to ten minutes of easy bike, walk, or skipping), then specific: empty-bar or light sets of the main lift, gradually adding load until you reach working sets. For upper-body days, include shoulder-friendly patterns such as band pull-aparts or light rows.
Mobility is the range you can actively control, not just passive stretching. If a position limits your lift (e.g. overhead squat depth), address it with targeted drills a few times per week rather than random foam rolling for an hour.
Try this: For your main lift, use three to five warm-up sets with bigger jumps early and smaller jumps as you approach working weight. End the warm-up feeling ready, not fatigued.