Tomb Raider: Legend
42 Achievements
13-15h
Have a Good Time All the Time
Complete all levels while in Time Trial mode
5.3%
How to unlock the Have a Good Time All the Time achievement in Tomb Raider: Legend - Definitive Guide
For this trophy you have to complete these levels successfully under the given time, they are really easy so don't worry about them. I finished the majority of them with minutes to spare. For more tips see the roadmap.
Level 1: Bolivia
Level 2: Peru
Level 3: Japan
Level 4: Ghana
Level 5: Kazakhstan
Level 6: England
Level 7: Nepal
See the according trophies within this guide (Good time on levels 1 - 7) for a very handy speedrun video which will show you how to do the puzzles as quick as you can etc.
You also have to complete the final boss time trial which is on the level Bolivia Redux, its par time is 4mins something but that is easily obtainable. It's a lot easier to kill the thing on time trial mode than it is on hard, here's a video for it anyway. Credit to nextgenwalkthroughs for the vid:
Tomb Raider Legend - Bolivia Redux Time Trial - YouTube