"费力前行"用英语可以说作"to make a hard effort to move forward" 或 "to struggle forward".
其中 "hard effort" 意为费力， "struggle" 意为奋斗。 "forward" 意为前进。
例句:
"He was making a hard effort to move forward through the deep snow." (他在费力地穿过深雪前进。)
"Despite the difficulties, they decided to struggle forward with their project." (尽管有困难，他们决定继续奋斗着完成他们的项目。)