Since some challenges of this new week are not easy to achieve, we offer you, below, a summary, with our tips to succeed as quickly as possible.
Each validated challenge will allow you to recover 20 XP, except for legendary quests, where 000 XP will be recoverable. This week honors Valentine's Day, as you can see.
The challenges, rewards and tips for week 145 season 5, Fortnite

Walk the distance under the sand (500)
Reward: 20 000 Season EXP- How to pass the challenge?
- A fairly simple challenge, since you only have to go to the desert and run 500 while being buried in the sand.

Stay within 5m of opponents for 20s while buried in the sand (5)
Reward: 20 000 Season EXP- How to pass the challenge?
- Again, you're going to have to go to the desert and get absorbed in the quicksand. Then stay 5 seconds near an enemy. The start of the game is conducive to succeeding in this challenge, or the Team Rumble mode.

Spend bullion (500)
Reward: 20 000 Season EXP- How to pass the challenge?
- To validate this challenge, just talk to an NPC and improve a weapon, for example, to spend gold bars.

Buy an item from a character (1)
Reward: 20 000 Season EXP- How to pass the challenge?
- Talk to a character and buy any item to complete the challenge.

Upgrade a weapon (1)
Reward: 20 000 Season EXP- How to pass the challenge?
- To complete this challenge, all you have to do is visit one of the many NPCs and spend gold bars to upgrade your weapon.

Obtain information from a character (1)
Reward: 20 Season XP- How to pass the challenge?
- Nothing complicated here, since you just have to go see an NPC and recruit him. However, we explain how to do it if you need help in this special guide.

Recruit a character (1)
Reward: 20 Season XP- How to pass the challenge?
- If you don't know how to validate your challenge, we give you some tips here.

Challenge characters to a duel
Reward: 55 Season XP- How to pass the challenge?
- This is a legendary quest. To do this, you just need to provoke 5, 10, 15, 20 and 25 characters into a duel. We explain how to do it here.