Challenging — Describes something that is very difficult to achieve. (Adj)

Accomplish

Achievement

Balance

Budget

Commitment

Concentrate

Constant

Deadline

Decrease

Differentiate

Discard

Disorganisation

Eliminate

Evaluate

Expertise

External

Fatigue

Frequent

Impose

Interruption

Interval

Invest

Mess

Misleading

Moodiness

Overwhelming

Personality

Preparation

Prioritise

Productive

Record

Regardless

Relate

Reward

Rid

Schedule

Select

Self-disciplined

Self-motivated

Time-consuming

Unpleasant

Urgent

Valuable

Wisely

The world is not comprehensible, but it is embraceable: through the embracing of one of its beings.

Stop being afraid of what could go wrong and think of what could go right.

Theater dates very quickly.

As soon as the doctor said I could start training again, I was on the treadmill the very next day. Once I got back into it, I worked out two or three times daily.